{"id":900,"date":"2021-07-13T07:04:44","date_gmt":"2021-07-13T12:04:44","guid":{"rendered":"https:\/\/www.knownhost.com\/kb\/?p=900"},"modified":"2021-12-08T07:05:11","modified_gmt":"2021-12-08T13:05:11","slug":"testing-remote-smtp-mail-server-connections","status":"publish","type":"post","link":"https:\/\/www.knownhost.com\/kb\/testing-remote-smtp-mail-server-connections\/","title":{"rendered":"Testing Remote SMTP \/ Mail Server Connections"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_82_2 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\/testing-remote-smtp-mail-server-connections\/#testing_with_telnet\" >Testing with Telnet<\/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\/testing-remote-smtp-mail-server-connections\/#testing_smtp_with_mx_toolbox\" >Testing SMTP with MX Toolbox<\/a><\/li><\/ul><\/nav><\/div>\n\n<p>When attempting to resolve mail server errors\/issues, being able to test the connection to a remote SMTP server is a critical step.<\/p>\n\n\n\n<p>Testing a remote SMTP \/ mail server connection should be done from both a local machine (computer) and the <a href=\"https:\/\/www.knownhost.com\/kb\/how-to-connect-with-ssh\/\">server<\/a> experiencing the issue.<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>If a connection can be made from both locations, the error is most likely not connectivity related.<\/li><li>If a connection can be made from a local machine, but NOT from the server (sending the mail), the issue is with the mail server sending the mail. You&#8217;ll want to review firewall settings or check IP blacklist information.<\/li><li>If a connection can NOT be made from either machine, it is most likely an issue with the remote (receiving) mail server and not resolvable.<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"testing_with_telnet\"><\/span>Testing with Telnet<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>From your terminal (shell) window perform the following:<\/p>\n\n\n\n<p>Dig for the MX record of the domain the email is being sent to. Eg. user@hotmail.com<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>  dig MX hotmail.com +short\n  5 mx2.hotmail.com.\n  5 mx3.hotmail.com.\n  5 mx4.hotmail.com.\n  5 mx1.hotmail.com.<\/code><\/pre>\n\n\n\n<p>Any of the listed will work, for this we&#8217;ll use mx1.hotmail.com. Now, let&#8217;s attempt the connection via port 25.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>  telnet mx1.hotmail.com 25<\/code><\/pre>\n\n\n\n<p>The referenced command should respond with something similar to the following if the connection was SUCCESSFUL:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>  Trying 65.54.188.126...\n  Connected to mx1.hotmail.com.\n  Escape character is '^]'.\n  220 BAY004-MC4F30.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http:\/\/privacy.microsoft.com\/en-us\/anti-spam.mspx. Sun, 1 Feb 2015 08:27:01 -0800<\/code><\/pre>\n\n\n\n<p>If the connection was NOT successful, you&#8217;ll see something like this:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>  Trying 65.54.188.126...\n  telnet: Unable to connect to remote host: Connection refused<\/code><\/pre>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"testing_smtp_with_mx_toolbox\"><\/span>Testing SMTP with MX Toolbox<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p>It&#8217;s not my preferred method, however you can always try external services for SMTP server diagnostics.<\/p>\n\n\n\n<p>Vist&nbsp;<a href=\"http:\/\/mxtoolbox.com\/diagnostic.aspx\">MXToolBox&#8217;s Email Server Test<\/a>&nbsp;and provide the remote mail server (eg. mx1.hotmail.com) for a diagnostic report.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>When attempting to resolve mail server errors\/issues, being able to test the connection to a remote SMTP server is a critical step. Testing a remote SMTP \/ mail server connection should be done from both a local machine (computer) and the server experiencing the issue. If a connection can be made from both locations, the [&hellip;]<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[178,123,120,291,297],"class_list":["post-900","post","type-post","status-publish","format-standard","hentry","category-getting-started","tag-email","tag-linux","tag-mail","tag-smtp","tag-telnet"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.3 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Testing Remote SMTP \/ Mail Server Connections - KnownHost<\/title>\n<meta name=\"description\" content=\"In this guide, we will show you how to test SMTP mail servers connection on you premium KnownHost server. 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