{"id":5276,"date":"2026-03-12T02:20:10","date_gmt":"2026-03-12T02:20:10","guid":{"rendered":"https:\/\/emailwarmup.com\/blog\/?p=5276"},"modified":"2026-03-12T02:20:12","modified_gmt":"2026-03-12T02:20:12","slug":"how-to-fix-421-4-7-28-gmail-ip-rate-limited","status":"publish","type":"post","link":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/","title":{"rendered":"How To Fix 421 4.7.28 | Gmail IP Rate Limited"},"content":{"rendered":"\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"3322\" height=\"2114\" src=\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\" alt=\"421 4.7.28\" class=\"wp-image-5277\"\/><\/figure>\n\n\n\n<p>The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly, triggering spam protection mechanisms.&nbsp;<\/p>\n\n\n\n<p>Fix it by pausing email sends for 24-48 hours, verifying <a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/spf-record\/\">SPF<\/a>\/<a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/dkim\">DKIM<\/a>\/<a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/dmarc\">DMARC<\/a> authentication, cleaning your email list, and resuming at reduced volume.<\/p>\n\n\n\n<p>Rate limiting differs from reputation blocks \u2014 Gmail isn&#8217;t saying your mail is spam, just that you&#8217;re sending <em>too much too fast<\/em>.&nbsp;<\/p>\n\n\n\n<p>The fix requires patience (waiting) combined with behavioral changes (sending less). Attempting to bypass limits by switching IPs often backfires, as Gmail correlates sending infrastructure.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Quick skim \u2014 421 4.7.28 error overview<\/h2>\n\n\n\n<p>The 421 4.7.28 error indicates volume-based throttling rather than content rejection.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Attribute<\/td><td>Details<\/td><\/tr><tr><td>Error code<\/td><td>421 4.7.28<\/td><\/tr><tr><td>Category<\/td><td>Rate limiting \/ throttling<\/td><\/tr><tr><td>Meaning<\/td><td>IP sending unusual volume; temporarily blocked<\/td><\/tr><tr><td>Severity<\/td><td>Temporary (typically 24-48 hours)<\/td><\/tr><tr><td>Common causes<\/td><td>Volume spike, poor reputation, shared IP abuse<\/td><\/tr><tr><td>Fix approach<\/td><td>Pause \u2192 verify auth \u2192 clean list \u2192 resume slowly<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\">What does IP rate limited mean?<\/h2>\n\n\n\n<p>Gmail tracks sending patterns per IP address. When volume or velocity exceeds expected thresholds (relative to your IP&#8217;s history and reputation), Gmail throttles delivery to protect recipients from potential spam floods.<\/p>\n\n\n\n<p>Let\u2019s look at the difference between rate limit and domain reputation block:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Type<\/td><td>Cause<\/td><td>Recovery<\/td><\/tr><tr><td>Rate limit (4.7.28)<\/td><td>Too much too fast<\/td><td>Wait + slow down<\/td><\/tr><tr><td>Reputation block (5.7.1)<\/td><td>Content\/behavior flagged as spam<\/td><td>Fix practices + rebuild trust<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>Rate limits are easier to recover from \u2014 Gmail just wants you to slow down. Reputation blocks require behavioral change and sustained good practices.<\/p>\n\n\n\n<p>But why does Gmail limit the rate? Gmail protects against:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Shared IP abuse affecting other tenants<\/li>\n\n\n\n<li>Compromised accounts sending spam bursts<\/li>\n\n\n\n<li>Legitimate senders accidentally overwhelming infrastructure<\/li>\n\n\n\n<li>Misconfigured servers flooding recipients<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Why does this error occur?<\/h2>\n\n\n\n<p>Several patterns trigger Gmail&#8217;s rate limiting algorithms.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Volume spike<\/h3>\n\n\n\n<p>Sudden increases in sending volume trigger alarms:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Normal: 100 emails\/day \u2192 Today: 10,000 emails<\/li>\n\n\n\n<li>New campaign launch without warmup<\/li>\n\n\n\n<li>Batch processing accumulated queue<\/li>\n\n\n\n<li>Misconfigured automation sending loops<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Poor IP reputation<\/h3>\n\n\n\n<p>Low-reputation IPs face stricter limits:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>PSpam trap hits<\/li>\n\n\n\n<li>High bounce rates<\/li>\n\n\n\n<li>Authentication failures<\/li>\n\n\n\n<li>revious spam complaints<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Shared IP contamination<\/h3>\n\n\n\n<p>On shared sending infrastructure (common with ESPs):<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>IP receives complaints you didn&#8217;t cause<\/li>\n\n\n\n<li>Another tenant&#8217;s spam affects your reputation<\/li>\n\n\n\n<li>Provider doesn&#8217;t isolate bad actors quickly enough<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Third-party compromise<\/h3>\n\n\n\n<p>If using APIs or SMTP relay:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Hacked accounts in your system<\/li>\n\n\n\n<li>Compromised API keys sending spam<\/li>\n\n\n\n<li>Malicious actors using your infrastructure<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How do you fix 421 4.7.28?<\/h2>\n\n\n\n<p>Immediate response plus long-term changes prevent recurrence.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Pause sending<\/h3>\n\n\n\n<p>Stop all non-essential email immediately:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Halt marketing campaigns<\/li>\n\n\n\n<li>Pause automated sequences<\/li>\n\n\n\n<li>Continue only critical transactional mail<\/li>\n\n\n\n<li>Wait 24-48 hours minimum<\/li>\n<\/ul>\n\n\n\n<p>Continued sending while rate-limited extends the block duration.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Verify authentication<\/h3>\n\n\n\n<p>Confirm proper configuration (rate limiting often accompanies auth issues):<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Verify DKIM signing is active<\/li>\n\n\n\n<li>Confirm DMARC alignment passes<\/li>\n\n\n\n<li>Check SPF includes all sending IPs<\/li>\n<\/ul>\n\n\n\n<p>Run an <a href=\"https:\/\/emailwarmup.com\/email-deliverability-test\">email deliverability test<\/a> to verify authentication status.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Check IP reputation<\/h3>\n\n\n\n<p>Use Google Postmaster Tools to assess current standing:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Check for spam rate spikes<\/li>\n\n\n\n<li>Review IP reputation graphs<\/li>\n\n\n\n<li>Register your sending domain<\/li>\n\n\n\n<li>Monitor authentication pass rates<\/li>\n<\/ul>\n\n\n\n<p>Additionally, check <a href=\"https:\/\/emailwarmup.com\/blog\/email-blacklist\/how-to-check-if-your-email-is-blacklisted\/\">blacklist status<\/a> across major databases.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Clean your list<\/h3>\n\n\n\n<p>Poor list quality contributes to rate-limiting triggers:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Remove addresses that bounced<\/li>\n\n\n\n<li>Eliminate purchased or scraped addresses<\/li>\n\n\n\n<li>Suppress unengaged recipients (no opens in 6+ months)<\/li>\n\n\n\n<li>Verify addresses before sending with an <a href=\"https:\/\/emailwarmup.com\/email-validation-api\">email validation API<\/a><\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Resume gradually<\/h3>\n\n\n\n<p>After the waiting period:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Start at 10-20% of normal volume<\/li>\n\n\n\n<li>Increase slowly over 1-2 weeks<\/li>\n\n\n\n<li>Monitor for 4xx responses<\/li>\n\n\n\n<li>Pause immediately if rate limiting recurs<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Address shared IP issues<\/h3>\n\n\n\n<p>If using shared sending infrastructure:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Contact your ESP about the rate limiting<\/li>\n\n\n\n<li>Request dedicated IP (if volume justifies)<\/li>\n\n\n\n<li>Ask about IP isolation and reputation management<\/li>\n\n\n\n<li>Consider switching providers if issues persist<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\">How do you prevent future rate limiting?<\/h2>\n\n\n\n<p>Sustainable sending practices prevent triggering Gmail&#8217;s throttles.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Maintain consistent volume<\/h3>\n\n\n\n<p>Avoid dramatic spikes:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Spread large sends across days<\/li>\n\n\n\n<li>Use scheduled sending for campaigns<\/li>\n\n\n\n<li>Implement <a href=\"https:\/\/emailwarmup.com\/blog\/email-warmup-guide\/what-is-email-warmup\/\">warmup<\/a> for new infrastructure<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Monitor continuously<\/h3>\n\n\n\n<p>Watch for early warning signs:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Track 4xx deferral rates<\/li>\n\n\n\n<li>Monitor Postmaster Tools weekly<\/li>\n\n\n\n<li>Set alerts for bounce rate increases<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Separate mail streams<\/h3>\n\n\n\n<p>Use different IPs or subdomains for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Cold outreach<\/li>\n\n\n\n<li>Transactional mail (receipts, alerts)<\/li>\n\n\n\n<li>Marketing mail (newsletters, promotions)<\/li>\n<\/ul>\n\n\n\n<p>Reputation problems in one stream won&#8217;t contaminate others.<\/p>\n\n\n\n\n<!-- EmailWarmup \u2014 Email Errors Campaign CTA Section -->\n<section id=\"ew-email-errors-consult\" aria-label=\"Help fixing email errors\">\n  <style>\n    \/* Scoped, theme-safe resets *\/\n    #ew-email-errors-consult, #ew-email-errors-consult *{\n      box-sizing:border-box;\n      -webkit-hyphens:none!important; -ms-hyphens:none!important; hyphens:none!important;\n      word-break:normal!important; overflow-wrap:anywhere;\n      font-family:system-ui,-apple-system,Segoe UI,Inter,Roboto,Arial,sans-serif!important;\n      color:#0f1115;\n    }\n\n    \/* Section wrapper *\/\n    #ew-email-errors-consult{\n      --radius:16px; --gap:14px;\n      --ink:#0f1115; --muted:#475569;\n      --border:#e5e7eb; --surface:#ffffff;\n\n      --tile1:#e9f0ff;\n      --tile2:#ecffd7;\n      --tile3:#efeaff;\n      --tile4:#ffe9f1;\n\n      background:\n        radial-gradient(1400px 600px at 10% -10%, #eef2ff 0%, transparent 60%),\n        radial-gradient(1400px 600px at 110% 110%, #fff7ed 0%, transparent 60%),\n        var(--surface);\n      border:1px solid var(--border);\n      border-radius:var(--radius);\n      padding:18px;\n      margin:24px auto;\n      max-width:980px;\n      box-shadow:0 8px 22px rgba(15,17,21,.06);\n    }\n\n    \/* Intro *\/\n    #ew-email-errors-consult .intro{\n      text-align:center;\n      max-width:760px;\n      margin:0 auto 16px;\n    }\n    #ew-email-errors-consult .eyebrow{\n      display:inline-block;\n      margin:0 0 8px;\n      padding:6px 10px;\n      border-radius:999px;\n      background:#eff6ff;\n      border:1px solid #dbeafe;\n      font-size:12px;\n      font-weight:800;\n      color:#1d4ed8;\n      letter-spacing:.02em;\n      text-transform:uppercase;\n    }\n    #ew-email-errors-consult .title{\n      margin:0 0 8px;\n      font-size:28px;\n      line-height:1.15;\n      letter-spacing:-.02em;\n      font-weight:900;\n      color:var(--ink);\n    }\n    #ew-email-errors-consult .subtitle{\n      margin:0;\n      font-size:15px;\n      line-height:1.6;\n      color:var(--muted);\n    }\n    #ew-email-errors-consult .subtitle a{\n      color:#2563eb;\n      text-decoration:none;\n      font-weight:700;\n    }\n    #ew-email-errors-consult .subtitle a:hover{ text-decoration:underline; }\n\n    \/* Tiles *\/\n    #ew-email-errors-consult .tiles{\n      display:flex;\n      flex-wrap:wrap;\n      gap:var(--gap);\n      margin-top:18px;\n    }\n\n    #ew-email-errors-consult .tile{\n      flex:1 1 220px;\n      min-width:220px;\n      background:#fff;\n      border:1px solid rgba(0,0,0,.06);\n      border-radius:14px;\n      padding:14px;\n      display:flex;\n      gap:12px;\n      align-items:flex-start;\n      box-shadow:0 6px 18px rgba(15,17,21,.06);\n    }\n\n    #ew-email-errors-consult .t1{ background:var(--tile1); }\n    #ew-email-errors-consult .t2{ background:var(--tile2); }\n    #ew-email-errors-consult .t3{ background:var(--tile3); }\n    #ew-email-errors-consult .t4{ background:var(--tile4); }\n\n    \/* Icon bubble *\/\n    #ew-email-errors-consult .icon{\n      flex:0 0 36px;\n      width:36px;\n      height:36px;\n      border-radius:10px;\n      display:grid;\n      place-items:center;\n      background:#ffffffaa;\n      border:1px solid rgba(0,0,0,.06);\n      box-shadow:0 4px 10px rgba(15,17,21,.06);\n    }\n\n    \/* Text *\/\n    #ew-email-errors-consult .h3like{\n      display:block;\n      margin:0 0 4px;\n      font-size:16px;\n      font-weight:800;\n      letter-spacing:-.01em;\n      color:inherit;\n      text-decoration:none;\n    }\n    #ew-email-errors-consult p{\n      margin:0;\n      font-size:14px;\n      line-height:1.5;\n      color:var(--muted);\n    }\n\n    \/* Bottom panel *\/\n    #ew-email-errors-consult .bottom{\n      margin-top:16px;\n      background:#ffffff;\n      border:1px solid #e5e7eb;\n      border-radius:14px;\n      padding:16px;\n      box-shadow:0 6px 18px rgba(15,17,21,.05);\n    }\n\n    #ew-email-errors-consult .bottom p{\n      margin:0;\n      font-size:14px;\n      line-height:1.6;\n      color:var(--muted);\n    }\n\n    #ew-email-errors-consult .bottom strong{\n      color:var(--ink);\n    }\n\n    \/* CTA row *\/\n    #ew-email-errors-consult .cta{\n      display:flex;\n      justify-content:center;\n      width:100%;\n      margin-top:16px;\n    }\n\n    #ew-email-errors-consult .btn{\n      display:inline-flex;\n      align-items:center;\n      gap:10px;\n      padding:12px 18px;\n      border-radius:12px;\n      font-weight:800;\n      text-decoration:none;\n      background:#2563eb;\n      color:#fff!important;\n      box-shadow:0 8px 18px rgba(37,99,235,.25);\n      transition:transform .04s ease, background .2s ease;\n    }\n    #ew-email-errors-consult .btn:hover{ background:#1e40af; }\n    #ew-email-errors-consult .btn:active{ transform:translateY(1px); }\n\n    @media (max-width:640px){\n      #ew-email-errors-consult .title{ font-size:24px; }\n    }\n  <\/style>\n\n  <div class=\"intro\">\n    <div class=\"eyebrow\">Need help fixing an email error?<\/div>\n    <h2 class=\"title\">Still stuck after trying the fix?<\/h2>\n    <p class=\"subtitle\">\n      Some email errors are easy to clear. Others point to deeper deliverability issues involving authentication, sender reputation, blacklisting, routing, or mailbox provider policy. If you would rather have an expert review it, speak with an\n      <a href=\"https:\/\/emailwarmup.com\/email-deliverability-consultant\">email delieverability consultant<\/a>\n      for free and we can help diagnose the issue and fix it on your behalf.\n    <\/p>\n  <\/div>\n\n  <div class=\"tiles\" role=\"list\">\n    <article class=\"tile t1\" role=\"listitem\">\n      <div class=\"icon\" aria-hidden=\"true\">\n        <svg width=\"18\" height=\"18\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\">\n          <path d=\"M21 15a2 2 0 0 1-2 2H7l-4 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2z\"><\/path>\n        <\/svg>\n      <\/div>\n      <div>\n        <span class=\"h3like\">Root cause analysis<\/span>\n        <p>We look beyond the error message itself to find what is actually breaking delivery, trust, or inbox placement.<\/p>\n      <\/div>\n    <\/article>\n\n    <article class=\"tile t2\" role=\"listitem\">\n      <div class=\"icon\" aria-hidden=\"true\">\n        <svg width=\"18\" height=\"18\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\">\n          <path d=\"M20 6L9 17l-5-5\"><\/path>\n        <\/svg>\n      <\/div>\n      <div>\n        <span class=\"h3like\">Technical fixes handled for you<\/span>\n        <p>From SPF, DKIM, and DMARC to blacklist cleanup, DNS alignment, and sending setup, we can guide or implement the fix.<\/p>\n      <\/div>\n    <\/article>\n\n    <article class=\"tile t3\" role=\"listitem\">\n      <div class=\"icon\" aria-hidden=\"true\">\n        <svg width=\"18\" height=\"18\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\">\n          <path d=\"M12 20V10\"><\/path>\n          <path d=\"M18 20V4\"><\/path>\n          <path d=\"M6 20v-4\"><\/path>\n        <\/svg>\n      <\/div>\n      <div>\n        <span class=\"h3like\">Deliverability-first review<\/span>\n        <p>We assess whether the error is part of a bigger pattern hurting opens, replies, and overall campaign performance.<\/p>\n      <\/div>\n    <\/article>\n\n    <article class=\"tile t4\" role=\"listitem\">\n      <div class=\"icon\" aria-hidden=\"true\">\n        <svg width=\"18\" height=\"18\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\">\n          <path d=\"M12 12c2.8 0 5-2.2 5-5s-2.2-5-5-5-5 2.2-5 5 2.2 5 5 5z\"><\/path>\n          <path d=\"M2 22c1.5-4 5.5-6 10-6s8.5 2 10 6\"><\/path>\n        <\/svg>\n      <\/div>\n      <div>\n        <span class=\"h3like\">Free expert consultation<\/span>\n        <p>Talk to a real deliverability expert, get honest guidance, and see the next best step without pressure or upsells.<\/p>\n      <\/div>\n    <\/article>\n  <\/div>\n\n  <div class=\"bottom\">\n    <p>\n      <strong>When should you book a consultation?<\/strong> If the error keeps coming back, affects multiple mailboxes or domains, started after an ESP or DNS change, or is tied to spam placement, low inboxing, high bounce rates, or authentication failures, it is usually faster to get an expert involved early.\n    <\/p>\n  <\/div>\n\n  <div class=\"cta\">\n    <a class=\"btn\" href=\"https:\/\/emailwarmup.com\/email-deliverability-consultant\" target=\"_blank\" rel=\"noopener\">\n      Talk to a deliverability expert for free\n      <svg width=\"18\" height=\"18\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\" aria-hidden=\"true\">\n        <path d=\"M5 12h14\"><\/path>\n        <path d=\"M12 5l7 7-7 7\"><\/path>\n      <\/svg>\n    <\/a>\n  <\/div>\n<\/section>\n\n\n\n\n\n<h2 class=\"wp-block-heading\">Frequently asked questions<\/h2>\n\n\n\n<p>Here are some commonly asked questions about this error:<\/p>\n\n\n\n<div class=\"schema-faq wp-block-yoast-faq-block\"><div class=\"schema-faq-section\" id=\"faq-question-1773279135746\"><strong class=\"schema-faq-question\">How long does rate limiting last?<\/strong> <p class=\"schema-faq-answer\">Typically, 24-48 hours if you stop sending. Continued attempts during the block extend the duration. After the limit lifts, resume gradually \u2014 jumping back to full volume may trigger re-limiting.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1773279142327\"><strong class=\"schema-faq-question\">Will switching IPs bypass the limit?<\/strong> <p class=\"schema-faq-answer\">Rarely works and often backfires. Gmail correlates sending infrastructure (domain, authentication, content patterns). Switching IPs while exhibiting the same behavior looks like deliberate evasion \u2014 a spam signal that worsens reputation.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1773279147785\"><strong class=\"schema-faq-question\">Is 421 4.7.28 different from 421 4.7.0?<\/strong> <p class=\"schema-faq-answer\">Yes. The 4.7.28 code specifically indicates rate limiting (volume concern). The 4.7.0 code is broader \u2014 covering suspicious content, authentication issues, and general policy concerns. Both are temporary, but fixes differ: 4.7.28 requires slowing down, while 4.7.0 often requires authentication or content fixes.<\/p> <\/div> <\/div>\n","protected":false},"excerpt":{"rendered":"<p>The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly, triggering spam protection mechanisms.&nbsp; Fix it by pausing email sends for 24-48 hours, verifying SPF\/DKIM\/DMARC authentication, cleaning your email list, and resuming at reduced volume. Rate limiting differs from reputation blocks \u2014 Gmail isn&#8217;t saying your [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":5277,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","footnotes":""},"categories":[38],"tags":[],"class_list":["post-5276","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-email-errors"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v25.0 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How To Fix 421 4.7.28 | Gmail IP Rate Limited<\/title>\n<meta name=\"description\" content=\"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let&#039;s learn how to fix it\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How To Fix 421 4.7.28 | Gmail IP Rate Limited\" \/>\n<meta property=\"og:description\" content=\"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let&#039;s learn how to fix it\" \/>\n<meta property=\"og:url\" content=\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\" \/>\n<meta property=\"og:site_name\" content=\"Email Warmup\" \/>\n<meta property=\"article:published_time\" content=\"2026-03-12T02:20:10+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2026-03-12T02:20:12+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"3322\" \/>\n\t<meta property=\"og:image:height\" content=\"2114\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Daniyal Dehleh\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Daniyal Dehleh\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"5 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\"},\"author\":{\"name\":\"Daniyal Dehleh\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/fb2aa8d9a54b3d4d28e96de4d49361a5\"},\"headline\":\"How To Fix 421 4.7.28 | Gmail IP Rate Limited\",\"datePublished\":\"2026-03-12T02:20:10+00:00\",\"dateModified\":\"2026-03-12T02:20:12+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\"},\"wordCount\":1017,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/#organization\"},\"image\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\",\"articleSection\":[\"Email Errors\"],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#respond\"]}]},{\"@type\":[\"WebPage\",\"FAQPage\"],\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\",\"url\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\",\"name\":\"How To Fix 421 4.7.28 | Gmail IP Rate Limited\",\"isPartOf\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\",\"datePublished\":\"2026-03-12T02:20:10+00:00\",\"dateModified\":\"2026-03-12T02:20:12+00:00\",\"description\":\"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let's learn how to fix it\",\"breadcrumb\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#breadcrumb\"},\"mainEntity\":[{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746\"},{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327\"},{\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785\"}],\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage\",\"url\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\",\"contentUrl\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg\",\"width\":3322,\"height\":2114,\"caption\":\"421 4.7.28\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/emailwarmup.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"How To Fix 421 4.7.28 | Gmail IP Rate Limited\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#website\",\"url\":\"https:\/\/emailwarmup.com\/blog\/\",\"name\":\"Email WarmUp\",\"description\":\"100% Inbox Guaranteed.\",\"publisher\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/emailwarmup.com\/blog\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#organization\",\"name\":\"Email WarmUp\",\"url\":\"https:\/\/emailwarmup.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/Group-42350.png\",\"contentUrl\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/Group-42350.png\",\"width\":400,\"height\":271,\"caption\":\"Email WarmUp\"},\"image\":{\"@id\":\"https:\/\/emailwarmup.com\/blog\/#\/schema\/logo\/image\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/fb2aa8d9a54b3d4d28e96de4d49361a5\",\"name\":\"Daniyal Dehleh\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/image-2.png\",\"contentUrl\":\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/image-2.png\",\"caption\":\"Daniyal Dehleh\"},\"description\":\"Daniyal is an award-winning email marketing and deliverability consultant trusted by global brands like LA Fitness, Remax, and Deel. With a proven record of boosting open rates, click-throughs, and ROI by 300% or more, he is recognized as a renowned email marketing expert. For over a decade, he has refined a top-down optimization strategy that aligns technical infrastructure, creative execution, and a tight feedback loop into a system that delivers consistent results for companies of all sizes. Now, Daniyal is pulling back the curtain to share the proven frameworks and insights he\u2019s gathered\u2014helping businesses worldwide achieve the highest possible ROI from their email programs.\",\"url\":\"https:\/\/emailwarmup.com\/blog\/author\/daniyaldehleh\/\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746\",\"position\":1,\"url\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746\",\"name\":\"How long does rate limiting last?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Typically, 24-48 hours if you stop sending. Continued attempts during the block extend the duration. After the limit lifts, resume gradually \u2014 jumping back to full volume may trigger re-limiting.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327\",\"position\":2,\"url\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327\",\"name\":\"Will switching IPs bypass the limit?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Rarely works and often backfires. Gmail correlates sending infrastructure (domain, authentication, content patterns). Switching IPs while exhibiting the same behavior looks like deliberate evasion \u2014 a spam signal that worsens reputation.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Question\",\"@id\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785\",\"position\":3,\"url\":\"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785\",\"name\":\"Is 421 4.7.28 different from 421 4.7.0?\",\"answerCount\":1,\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. The 4.7.28 code specifically indicates rate limiting (volume concern). The 4.7.0 code is broader \u2014 covering suspicious content, authentication issues, and general policy concerns. Both are temporary, but fixes differ: 4.7.28 requires slowing down, while 4.7.0 often requires authentication or content fixes.\",\"inLanguage\":\"en-US\"},\"inLanguage\":\"en-US\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"How To Fix 421 4.7.28 | Gmail IP Rate Limited","description":"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let's learn how to fix it","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/","og_locale":"en_US","og_type":"article","og_title":"How To Fix 421 4.7.28 | Gmail IP Rate Limited","og_description":"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let's learn how to fix it","og_url":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/","og_site_name":"Email Warmup","article_published_time":"2026-03-12T02:20:10+00:00","article_modified_time":"2026-03-12T02:20:12+00:00","og_image":[{"width":3322,"height":2114,"url":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg","type":"image\/jpeg"}],"author":"Daniyal Dehleh","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Daniyal Dehleh","Est. reading time":"5 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#article","isPartOf":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/"},"author":{"name":"Daniyal Dehleh","@id":"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/fb2aa8d9a54b3d4d28e96de4d49361a5"},"headline":"How To Fix 421 4.7.28 | Gmail IP Rate Limited","datePublished":"2026-03-12T02:20:10+00:00","dateModified":"2026-03-12T02:20:12+00:00","mainEntityOfPage":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/"},"wordCount":1017,"commentCount":0,"publisher":{"@id":"https:\/\/emailwarmup.com\/blog\/#organization"},"image":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage"},"thumbnailUrl":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg","articleSection":["Email Errors"],"inLanguage":"en-US","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#respond"]}]},{"@type":["WebPage","FAQPage"],"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/","url":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/","name":"How To Fix 421 4.7.28 | Gmail IP Rate Limited","isPartOf":{"@id":"https:\/\/emailwarmup.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage"},"image":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage"},"thumbnailUrl":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg","datePublished":"2026-03-12T02:20:10+00:00","dateModified":"2026-03-12T02:20:12+00:00","description":"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly. Let's learn how to fix it","breadcrumb":{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#breadcrumb"},"mainEntity":[{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746"},{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327"},{"@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785"}],"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#primaryimage","url":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg","contentUrl":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg","width":3322,"height":2114,"caption":"421 4.7.28"},{"@type":"BreadcrumbList","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/emailwarmup.com\/blog\/"},{"@type":"ListItem","position":2,"name":"How To Fix 421 4.7.28 | Gmail IP Rate Limited"}]},{"@type":"WebSite","@id":"https:\/\/emailwarmup.com\/blog\/#website","url":"https:\/\/emailwarmup.com\/blog\/","name":"Email WarmUp","description":"100% Inbox Guaranteed.","publisher":{"@id":"https:\/\/emailwarmup.com\/blog\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/emailwarmup.com\/blog\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/emailwarmup.com\/blog\/#organization","name":"Email WarmUp","url":"https:\/\/emailwarmup.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/emailwarmup.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/Group-42350.png","contentUrl":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/Group-42350.png","width":400,"height":271,"caption":"Email WarmUp"},"image":{"@id":"https:\/\/emailwarmup.com\/blog\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/fb2aa8d9a54b3d4d28e96de4d49361a5","name":"Daniyal Dehleh","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/emailwarmup.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/image-2.png","contentUrl":"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2025\/05\/image-2.png","caption":"Daniyal Dehleh"},"description":"Daniyal is an award-winning email marketing and deliverability consultant trusted by global brands like LA Fitness, Remax, and Deel. With a proven record of boosting open rates, click-throughs, and ROI by 300% or more, he is recognized as a renowned email marketing expert. For over a decade, he has refined a top-down optimization strategy that aligns technical infrastructure, creative execution, and a tight feedback loop into a system that delivers consistent results for companies of all sizes. Now, Daniyal is pulling back the curtain to share the proven frameworks and insights he\u2019s gathered\u2014helping businesses worldwide achieve the highest possible ROI from their email programs.","url":"https:\/\/emailwarmup.com\/blog\/author\/daniyaldehleh\/"},{"@type":"Question","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746","position":1,"url":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279135746","name":"How long does rate limiting last?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Typically, 24-48 hours if you stop sending. Continued attempts during the block extend the duration. After the limit lifts, resume gradually \u2014 jumping back to full volume may trigger re-limiting.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327","position":2,"url":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279142327","name":"Will switching IPs bypass the limit?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Rarely works and often backfires. Gmail correlates sending infrastructure (domain, authentication, content patterns). Switching IPs while exhibiting the same behavior looks like deliberate evasion \u2014 a spam signal that worsens reputation.","inLanguage":"en-US"},"inLanguage":"en-US"},{"@type":"Question","@id":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785","position":3,"url":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-421-4-7-28-gmail-ip-rate-limited\/#faq-question-1773279147785","name":"Is 421 4.7.28 different from 421 4.7.0?","answerCount":1,"acceptedAnswer":{"@type":"Answer","text":"Yes. The 4.7.28 code specifically indicates rate limiting (volume concern). The 4.7.0 code is broader \u2014 covering suspicious content, authentication issues, and general policy concerns. Both are temporary, but fixes differ: 4.7.28 requires slowing down, while 4.7.0 often requires authentication or content fixes.","inLanguage":"en-US"},"inLanguage":"en-US"}]}},"uagb_featured_image_src":{"full":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",3322,2114,false],"thumbnail":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",150,95,false],"medium":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",300,191,false],"medium_large":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",768,489,false],"large":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",1024,652,false],"1536x1536":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",1536,977,false],"2048x2048":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",2048,1303,false],"profile_24":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",24,15,false],"profile_48":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",48,31,false],"profile_96":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",96,61,false],"profile_150":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",150,95,false],"profile_300":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/421-4.7.28-_11zon.jpg",300,191,false]},"uagb_author_info":{"display_name":"Daniyal Dehleh","author_link":"https:\/\/emailwarmup.com\/blog\/author\/daniyaldehleh\/"},"uagb_comment_info":0,"uagb_excerpt":"The 421 4.7.28 error means Gmail has temporarily rate-limited your IP address \u2014 too many messages sent too quickly, triggering spam protection mechanisms.&nbsp; Fix it by pausing email sends for 24-48 hours, verifying SPF\/DKIM\/DMARC authentication, cleaning your email list, and resuming at reduced volume. Rate limiting differs from reputation blocks \u2014 Gmail isn&#8217;t saying your&hellip;","_links":{"self":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5276","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/comments?post=5276"}],"version-history":[{"count":1,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5276\/revisions"}],"predecessor-version":[{"id":5278,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5276\/revisions\/5278"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/media\/5277"}],"wp:attachment":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/media?parent=5276"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/categories?post=5276"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/tags?post=5276"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}