{"id":313,"date":"2020-11-26T10:58:29","date_gmt":"2020-11-25T23:58:29","guid":{"rendered":"http:\/\/www.chris-newby.com\/?p=313"},"modified":"2021-11-08T13:17:40","modified_gmt":"2021-11-08T02:17:40","slug":"testing-smtp-via-telnet","status":"publish","type":"post","link":"https:\/\/ale.newby.work\/?p=313","title":{"rendered":"Testing SMTP via Telnet"},"content":{"rendered":"\n<ol class=\"wp-block-list\"><li>Open a command prompt.<br><\/li><li>Type the following command: telnet &lt;mail server name or IP&gt; 25<ul><li>You should receive output similar to the following:<br><strong>220 remote.mailserveraddress.com ESMTP<\/strong> <object data=\"\/\/www.dellcdn.com\/support\/staticcdn\/core\/svg\/src\/alert-info-blue.svg\" type=\"image\/svg+xml\"><\/object>NOTE: Once the telnet session is established, the Backspace and Delete keys do not work. If a typo is made, press Enter and retry the command. In some cases, it may be necessary to close the telnet session and reconnect.<\/li><li>If you receive an error similar to <strong>Could not open connection to the host, on port 25: Connect failed<\/strong>, this indicates that your machine could not establish a telnet session with the destination server using port 25. If you initially attempted to connect using the destination server&#8217;s name, try to connect using its IP address instead. If this is successful, you likely have a DNS issue. If you are unable to connect using the destination server&#8217;s name or IP address, port 25 is being blocked somewhere between your machine and the destination server. The issue is probably due to a firewall on the destination server&#8217;s end, but it can also be caused by a network misconfiguration or firewall on your end.<\/li><li>If you receive output similar to the following:<br><strong>554-remote.mailserveraddress.com<br>554 Your connection has been blocked due to low sender reputation&#8230;<br>Connection to host lost.<\/strong><br>The public IP address associated with your mail server has developed a bad reputation. If you recently acquired this IP address, its previous owner likely sent spam from it, and your best option may be to request a different address from your ISP. If this is not feasible, there are other options, but there is not always a quick or easy solution to this issue. The error message may include additional instructions for resolving the issue. If not, <a href=\"http:\/\/www.danrichard.com\/2011\/03\/18\/how-to-fix-554-your-access-to-this-mail-system-has-been-rejected-due-to-the-sending-mtas-poor-reputation\/\" target=\"_blank\" rel=\"noreferrer noopener\"><u>this blog entry<\/u><\/a> has a number of suggestions. Unfortunately, it may simply be a matter of waiting for your address&#8217;s reputation to improve, and this can take considerable time.<\/li><\/ul><\/li><li>Type: EHLO <em>&lt;mail server internet name&gt;<\/em><br>Replace <em>&lt;mail server internet name&gt;<\/em> with your mail server&#8217;s public fully qualified domain name &#8211; for instance, mail.dell.com.<br><\/li><li>Type: mail from: <em>&lt;your_name@yourdomain.com&gt;<\/em> and press Enter.<br><\/li><li>Type: rcpt to: <em>&lt;recipient@recipientdomain.com&gt;<\/em> and press Enter.<br><\/li><li>Type: data and press Enter.<br><\/li><li>Type: Subject: <em>&lt;a subject here&gt;<\/em> and press Enter.<br><\/li><li>Type: This is a test message sent from telnet. and press Enter.<br><\/li><li>Type: . and press Enter<br>The message should be accepted for delivery.<\/li><\/ol>\n","protected":false},"excerpt":{"rendered":"<p>Open a command prompt. Type the following command: telnet &lt;mail server name or IP&gt; 25&#8230;<\/p>\n<div class=\"more-link-wrapper\"><a class=\"more-link\" href=\"https:\/\/ale.newby.work\/?p=313\">Read the post<span class=\"screen-reader-text\">Testing SMTP via Telnet<\/span><\/a><\/div>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-313","post","type-post","status-publish","format-standard","hentry","category-alcatel","excerpt","zoom","full-without-featured","even","excerpt-0"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Testing SMTP via Telnet - ALE @ Newby.Work<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/ale.newby.work\/?p=313\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Testing SMTP via Telnet - ALE @ Newby.Work\" \/>\n<meta property=\"og:description\" content=\"Open a command prompt. 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