{"id":5237,"date":"2026-03-09T19:50:52","date_gmt":"2026-03-09T19:50:52","guid":{"rendered":"https:\/\/emailwarmup.com\/blog\/?p=5237"},"modified":"2026-03-09T19:50:58","modified_gmt":"2026-03-09T19:50:58","slug":"how-to-fix-550-5-7-30-dkim-authentication-failed","status":"publish","type":"post","link":"https:\/\/emailwarmup.com\/blog\/email-errors\/how-to-fix-550-5-7-30-dkim-authentication-failed\/","title":{"rendered":"How To Fix 550 5.7.30 | DKIM Authentication Failed"},"content":{"rendered":"\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"3154\" height=\"2007\" src=\"https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg\" alt=\"550 5.7.30\" class=\"wp-image-5238\"\/><\/figure>\n\n\n\n<p>The 550 5.7.30 error means the receiving server rejected your email because <a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/dkim\">DKIM<\/a> signature validation failed \u2014 the cryptographic signature in your email didn&#8217;t match the public key in DNS, or no valid signature existed.\u00a0<\/p>\n\n\n\n<p>Fix it by verifying your DKIM TXT record is correctly published, ensuring your mail server signs outgoing messages, and confirming the public key matches what your email service provides.<\/p>\n\n\n\n<p>DKIM failures indicate either DNS misconfiguration or signing problems at the mail server level. Unlike<a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/spf-record\/\"> SPF<\/a> (which checks sending IPs), DKIM verifies message integrity \u2014 a failed signature suggests tampering or misconfiguration, both of which are concerning signals to receiving servers.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Quick skim \u2014 550 5.7.30 error overview<\/h2>\n\n\n\n<p>The 550 5.7.30 error indicates DKIM-specific authentication failure.<\/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>550 5.7.30<\/td><\/tr><tr><td>Category<\/td><td>Authentication\/signature failure<\/td><\/tr><tr><td>Meaning<\/td><td>DKIM signature invalid or missing<\/td><\/tr><tr><td>Severity<\/td><td>Permanent (requires DNS and server configuration)<\/td><\/tr><tr><td>Common causes<\/td><td>Missing DNS record, signing disabled, key mismatch<\/td><\/tr><tr><td>Fix approach<\/td><td>Verify DNS record \u2192 enable signing \u2192 test validation<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>If you&#8217;re seeing broader DKIM failures beyond this error code, see our full guide on <a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/dkim-fail\/\">DKIM Fail Explained<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How do you fix a DKIM authentication failure?<\/h2>\n\n\n\n<p>Systematic verification identifies whether the problem is DNS, signing, or both.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Verify the DKIM record exists<\/h3>\n\n\n\n<p>Check DNS for your DKIM public key:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>dig TXT selector1._domainkey.yourdomain.com<\/code><\/pre>\n\n\n\n<p>Replace selector1 with your actual selector (provided by your email service). Use the <a href=\"https:\/\/emailwarmup.com\/dkim-lookup\">DKIM lookup tool<\/a> for automated checking.<\/p>\n\n\n\n<p>The response should include a TXT record starting with v=DKIM1; containing your public key.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Get the correct record from the provider<\/h3>\n\n\n\n<p>Each email service provides specific DKIM records:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Google Workspace: Admin Console \u2192 Apps \u2192 Gmail \u2192 Authenticate email<\/li>\n\n\n\n<li>Microsoft 365: Defender portal \u2192 Email authentication \u2192 DKIM<\/li>\n\n\n\n<li>SendGrid, Mailgun, etc.: Dashboard \u2192 Domain authentication settings<\/li>\n<\/ul>\n\n\n\n<p>Copy the exact TXT record value (including selector name) from your provider.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Add\/update DNS record<\/h3>\n\n\n\n<p>In your DNS provider&#8217;s control panel:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Create a TXT record<\/li>\n\n\n\n<li>Host\/Name: selector._domainkey (selector from provider)<\/li>\n\n\n\n<li>Value: The full public key string from the provider<\/li>\n<\/ul>\n\n\n\n<p>For long keys, some DNS providers require splitting across multiple strings or have specific formatting. Check provider documentation.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Verify key format<\/h3>\n\n\n\n<p>Common formatting issues:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Missing v=DKIM1; prefix<\/li>\n\n\n\n<li>Missing p= before the public key<\/li>\n\n\n\n<li>Extra whitespace or newlines in the key<\/li>\n\n\n\n<li>Key truncated by character limits<\/li>\n<\/ul>\n\n\n\n<p>The record should look like:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GN...<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">Enable signing on the mail server<\/h3>\n\n\n\n<p>For self-hosted mail servers, verify DKIM signing is active:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Postfix with OpenDKIM: Check \/etc\/opendkim.conf and signing table<\/li>\n\n\n\n<li>Exchange: Enable DKIM in Exchange Admin Center<\/li>\n\n\n\n<li>Cloud providers: Enable in the authentication settings dashboard<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Wait for propagation<\/h3>\n\n\n\n<p>After DNS changes:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Allow 15-60 minutes for initial propagation<\/li>\n\n\n\n<li>Some resolvers cache for longer<\/li>\n\n\n\n<li>Test from multiple locations if results are inconsistent<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Test validation<\/h3>\n\n\n\n<p>Send a test message and verify DKIM passes:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Send to a Gmail account and check Authentication-Results header<\/li>\n\n\n\n<li>Use verification services (mail-tester.com, etc.)<\/li>\n\n\n\n<li>Run a <a href=\"https:\/\/emailwarmup.com\/email-deliverability-test\">email deliverability test<\/a><\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">How do you prevent DKIM failures?<\/h2>\n\n\n\n<p>DKIM requires maintenance during infrastructure changes and key rotation.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Document key configuration<\/h3>\n\n\n\n<p>Track for each sending domain:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Selector name<\/li>\n\n\n\n<li>Key publication date<\/li>\n\n\n\n<li>Which service uses which selector<\/li>\n\n\n\n<li>Key rotation schedule<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Monitor authentication<\/h3>\n\n\n\n<p>Check DMARC aggregate reports for DKIM failures. Sudden increases indicate:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>DNS record issues<\/li>\n\n\n\n<li>Signing configuration changes<\/li>\n\n\n\n<li>Unauthorized senders attempting to spoof<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\">Rotate keys periodically<\/h3>\n\n\n\n<p>DKIM keys should rotate annually (or more frequently for high-security environments):<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Generate a new key pair with a new selector<\/li>\n\n\n\n<li>Publish new public key in DNS<\/li>\n\n\n\n<li>Update signing configuration to use the new selector<\/li>\n\n\n\n<li>Keep the old selector active during transition<\/li>\n\n\n\n<li>Remove the old selector after propagation<\/li>\n<\/ol>\n\n\n\n<h3 class=\"wp-block-heading\">Test after changes<\/h3>\n\n\n\n<p>Any change to the mail infrastructure warrants DKIM verification:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Provider migrations<\/li>\n\n\n\n<li>Server updates<\/li>\n\n\n\n<li>DNS provider changes<\/li>\n\n\n\n<li>Domain registrar transfers<\/li>\n<\/ul>\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; 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}\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-1773085733381\"><strong class=\"schema-faq-question\">What&#8217;s the difference between DKIM and SPF?<\/strong> <p class=\"schema-faq-answer\">SPF verifies <em>where<\/em> the email comes from (which IP addresses are authorized). DKIM verifies <em>what<\/em> the email contains (message integrity via cryptographic signature). Both contribute to <a href=\"https:\/\/emailwarmup.com\/blog\/email-authentication\/dmarc\">DMARC<\/a> evaluation, but they check different things.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1773085742056\"><strong class=\"schema-faq-question\">Why does DKIM fail when I&#8217;m using a third-party sender?<\/strong> <p class=\"schema-faq-answer\">Third-party services sign with their own domain by default (d=sendgrid.net), which doesn&#8217;t align with your From domain for DMARC. Configure custom DKIM with your domain through the provider&#8217;s authentication settings \u2014 they&#8217;ll give you a TXT record to publish.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1773085747214\"><strong class=\"schema-faq-question\">Can message forwarding break DKIM?<\/strong> <p class=\"schema-faq-answer\">Yes. If a forwarding service modifies headers or body content included in the DKIM signature, validation fails at the final destination. Mailing lists that add footers commonly cause this. DMARC&#8217;s fallback to SPF helps, but neither may pass for heavily modified forwards.<\/p> <\/div> <div class=\"schema-faq-section\" id=\"faq-question-1773085752266\"><strong class=\"schema-faq-question\">How do I know which selector to use?<\/strong> <p class=\"schema-faq-answer\">Your email service provider specifies the selector. Check their documentation or admin dashboard. Common patterns include selector1, google, s1, or provider-specific names. The selector in your DNS record must match what your mail server uses when signing.<\/p> <\/div> <\/div>\n","protected":false},"excerpt":{"rendered":"<p>The 550 5.7.30 error means the receiving server rejected your email because DKIM signature validation failed \u2014 the cryptographic signature in your email didn&#8217;t match the public key in DNS, or no valid signature existed.\u00a0 Fix it by verifying your DKIM TXT record is correctly published, ensuring your mail server signs outgoing messages, and confirming [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":5238,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","footnotes":""},"categories":[38],"tags":[],"class_list":["post-5237","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 550 5.7.30 | DKIM Authentication Failed<\/title>\n<meta name=\"description\" content=\"The 550 5.7.30 error means the receiving server rejected your email because DKIM signature validation failed. Let&#039;s find out 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-550-5-7-30-dkim-authentication-failed\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How To Fix 550 5.7.30 | DKIM Authentication Failed\" \/>\n<meta property=\"og:description\" content=\"The 550 5.7.30 error means the receiving server rejected your email because DKIM signature validation failed. 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The selector in your DNS record must match what your mail server uses when signing.","inLanguage":"en-US"},"inLanguage":"en-US"}]}},"uagb_featured_image_src":{"full":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",3154,2007,false],"thumbnail":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",150,95,false],"medium":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",300,191,false],"medium_large":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",768,489,false],"large":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",1024,652,false],"1536x1536":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",1536,977,false],"2048x2048":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",2048,1303,false],"profile_24":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",24,15,false],"profile_48":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",48,31,false],"profile_96":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",96,61,false],"profile_150":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_11zon.jpg",150,95,false],"profile_300":["https:\/\/emailwarmup.com\/blog\/wp-content\/uploads\/2026\/03\/550-5.7.30_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 550 5.7.30 error means the receiving server rejected your email because DKIM signature validation failed \u2014 the cryptographic signature in your email didn&#8217;t match the public key in DNS, or no valid signature existed.\u00a0 Fix it by verifying your DKIM TXT record is correctly published, ensuring your mail server signs outgoing messages, and confirming&hellip;","_links":{"self":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5237","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=5237"}],"version-history":[{"count":1,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5237\/revisions"}],"predecessor-version":[{"id":5239,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/posts\/5237\/revisions\/5239"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/media\/5238"}],"wp:attachment":[{"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/media?parent=5237"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/categories?post=5237"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emailwarmup.com\/blog\/wp-json\/wp\/v2\/tags?post=5237"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}