{"id":5771,"date":"2022-01-24T07:56:44","date_gmt":"2022-01-24T13:56:44","guid":{"rendered":"https:\/\/www.knownhost.com\/kb\/?p=5771"},"modified":"2023-03-03T06:43:48","modified_gmt":"2023-03-03T12:43:48","slug":"smtp-error-521","status":"publish","type":"post","link":"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/","title":{"rendered":"SMTP Error 521"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_83 ez-toc-wrap-right counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><a href=\"#\" class=\"ez-toc-pull-right ez-toc-btn ez-toc-btn-xs ez-toc-btn-default ez-toc-toggle\" aria-label=\"Toggle Table of Content\"><span class=\"ez-toc-js-icon-con\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #212121;color:#212121\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #212121;color:#212121\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/span><\/a><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1 eztoc-toggle-hide-by-default' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/#what_does_this_mean\" >What does this mean?<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/#aol_specific_reference\" >AOL Specific Reference<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/#aol_smtp_error_521_example\" >AOL SMTP Error 521 Example<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/#how_to_fix_smtp_error_521\" >How to fix SMTP Error 521?<\/a><\/li><\/ul><\/nav><\/div>\n\n<p><strong>Description<\/strong>: &lt;domain&gt; does not accept mail (see rfc1846).<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"what_does_this_mean\"><\/span>What does this mean?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>The recipient mail server does not actually accept and deliver email itself. From this point, emails can either fail or be relayed\/forwarded to another mail server. Most commonly, this is shown for relays.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"aol_specific_reference\"><\/span>AOL Specific Reference<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>If you received this error message in your inbox, it means that you tried to send someone at AOL an email message, and AOL\u2019s mail server rejected the connection because it\u2019s seen just a bit too much spam lately from your mail server. Ref:\u00a0<a href=\"https:\/\/blog.mailchannels.com\/2012\/09\/why-did-i-get-521-5-2-1-conb1-httppostmaster-info-aol-comerrors554conb1-html\">AOL 521<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"aol_smtp_error_521_example\"><\/span>AOL SMTP Error 521 Example<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<pre class=\"wp-block-code\"><code>521 5.2.1 : (CON:B1) http:\/\/postmaster.info.aol.com\/errors\/554conb1.html<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"how_to_fix_smtp_error_521\"><span class=\"ez-toc-section\" id=\"how_to_fix_smtp_error_521\"><\/span>How to fix SMTP Error 521?<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Check to ensure it is actually failing and not being relayed.<\/li>\n\n\n\n<li>If the email is actually failing, contact the recipient mail server to determine the reason for not accepting mail.<\/li>\n<\/ul>\n\n\n\n<p>For fixing the AOL Error Response, please see: <a href=\"https:\/\/blog.mailchannels.com\/2012\/09\/why-did-i-get-521-5-2-1-conb1-httppostmaster-info-aol-comerrors554conb1-html\" target=\"_blank\" rel=\"noreferrer noopener\">AOL What can I do?<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Description: &lt;domain&gt; does not accept mail (see rfc1846). What does this mean? The recipient mail server does not actually accept and deliver email itself. From this point, emails can either fail or be relayed\/forwarded to another mail server. Most commonly, this is shown for relays. AOL Specific Reference If you received this error message in [&hellip;]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[97],"tags":[576,380,291],"class_list":["post-5771","post","type-post","status-publish","format-standard","hentry","category-other","tag-576","tag-error","tag-smtp"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.6 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>SMTP Error 521 - KnownHost<\/title>\n<meta name=\"description\" content=\"KnownHost self-hosted email guide to help you troubleshoot and fix SMTP Error 521 on your premium KnownHost server.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.knownhost.com\/kb\/smtp-error-521\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"SMTP Error 521 - 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