{"id":8203,"date":"2021-09-28T17:33:53","date_gmt":"2021-09-28T12:03:53","guid":{"rendered":"https:\/\/www.skynats.com\/?p=8203"},"modified":"2026-06-03T20:24:14","modified_gmt":"2026-06-03T14:54:14","slug":"how-to-fix-550-permanent-smtp-error","status":"publish","type":"post","link":"https:\/\/www.skynats.com\/blog\/how-to-fix-550-permanent-smtp-error\/","title":{"rendered":"How to Fix &#8220;550 Permanent failure for one or more recipients&#8221; SMTP error?"},"content":{"rendered":"\r\n<p class=\"wp-block-paragraph\">We&#8217;ve received numerous inquiries from our clients about the &#8220;550 permanent failure for one or more recipients&#8221; error, particularly related to Gmail. This is an SMTP (Simple Mail Transfer Protocol) error, which typically occurs when the sending mail is blocked by the recipient&#8217;s mail hosting server.<\/p>\r\n\r\n\r\n\r\n<h2 id=\"h-what-causes-550-permanent-smtp-errors\" class=\"wp-block-heading has-normal-font-size\">What causes 550 permanent SMTP errors?<\/h2>\r\n\r\n\r\n\r\n<ol class=\"wp-block-list\">\r\n<li>The IP address of the sender&#8217;s server is blacklisted in the receiver&#8217;s mail hosting server.<\/li>\r\n\r\n\r\n\r\n<li>The email address of the recipient does not exist or is not found.<\/li>\r\n\r\n\r\n\r\n<li>In case of the recipient&#8217;s mail inbox is full and there is not enough space to receive any more mails.<\/li>\r\n\r\n\r\n\r\n<li>The recipient&#8217;s email is temporarily blocked.<\/li>\r\n\r\n\r\n\r\n<li>The recipient&#8217;s hosting server considers your mails are spam and hence the mail gets blocked.<\/li>\r\n<\/ol>\r\n\r\n\r\n\r\n<h2 id=\"h-how-to-fix-550-permanent-smtp-errors\" class=\"wp-block-heading has-normal-font-size\">How to fix 550 permanent SMTP errors?<\/h2>\r\n\r\n\r\n\r\n<ul class=\"wp-block-list\">\r\n<li><strong>Sender&#8217;s server IP blacklisted in receiver&#8217;s mail hosting server:<\/strong><\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If your server frequently sends spam or phishing emails, its IP may be blocked by the recipient server&#8217;s firewall, resulting in a &#8220;550 permanent failure for one or more recipients blocked&#8221; error. Additionally, many spam filtering tools today automatically detect and filter IPs or domains that send spam, which further contributes to IP blocking.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">You can check if your IP address is blacklisted using many tools which are available nowadays. For example, you can use the <a href=\"https:\/\/mxtoolbox.com\/\" target=\"_blank\" rel=\"noopener\">MX toolbox<\/a> tool for checking IP or domain blacklist.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If you are using a shared server there is the chance of sending spam from other domains that are hosted on your same server, so hence the IP address of the server will get blacklisted.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If you are using a dedicated server without a firewall or improper firewall configuration there is a chance of VPS getting hacked.<\/p>\r\n\r\n\r\n\r\n<ul class=\"wp-block-list\">\r\n<li><strong>Bad SPF Record for the domain<\/strong><\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">An SPF (Sender Policy Framework) record can be used to authorize a domain or IP from which mail is sent and it is a type of DNS TXT record.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If you have your own. and SPF record then there is a chance of the mail getting rejected by the recipient&#8217;s server.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">Having a valid SPF record will improve the authenticity and deliverability of your emails.<\/p>\r\n\r\n\r\n\r\n<ul class=\"wp-block-list\">\r\n<li><strong>Check if the recipient server has the correct MX record<\/strong><\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If the recipient&#8217;s server MX record is not valid it will not allow sending the mail from your server to that recipient.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">If you&#8217;re still facing the &#8220;550 permanent failure for one or more recipients Gmail&#8221; SMTP issue, it&#8217;s essential to identify the exact cause and implement a permanent solution. Our experienced technical support team, well-versed in resolving various mail server-related problems, is ready to assist you anytime. Feel free to <a href=\"https:\/\/www.skynats.com\/contact-us\/\">contact us<\/a> for help.<\/p>\r\n\r\n\r\n\r\n<p class=\"wp-block-paragraph\">&nbsp;<\/p>\r\n","protected":false},"excerpt":{"rendered":"<p>We&#8217;ve received numerous inquiries from our clients about the &#8220;550 permanent failure for one or more recipients&#8221; error, particularly related to Gmail. This is an SMTP (Simple Mail Transfer Protocol) error, which typically occurs when the sending mail is blocked by the recipient&#8217;s mail hosting server. What causes 550 permanent SMTP errors? How to fix [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[604,605],"class_list":["post-8203","post","type-post","status-publish","format-standard","hentry","category-blog","tag-550-permanent-failure","tag-smpt-error"],"_links":{"self":[{"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/posts\/8203","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/comments?post=8203"}],"version-history":[{"count":3,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/posts\/8203\/revisions"}],"predecessor-version":[{"id":17645,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/posts\/8203\/revisions\/17645"}],"wp:attachment":[{"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/media?parent=8203"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/categories?post=8203"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.skynats.com\/blog\/wp-json\/wp\/v2\/tags?post=8203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}