{"id":1322,"date":"2015-06-10T13:23:00","date_gmt":"2015-06-10T05:23:00","guid":{"rendered":"http:\/\/nick.txtcc.com\/?p=1322"},"modified":"2019-04-29T14:03:47","modified_gmt":"2019-04-29T06:03:47","slug":"send-a-test-mail-using-telnet","status":"publish","type":"post","link":"http:\/\/nick.txtcc.com\/index.php\/linux\/1322","title":{"rendered":"Send a test mail using Telnet"},"content":{"rendered":"
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Emulating an SMTP session with Telnet<\/h2>\nLet us try to send an email to the user now. As the “example.com” domain does not really existing your DNS settings will likely not point to the right server. So we are simulating an SMTP session with the telnet<\/em> command. Install the telnet package if you haven’t already:\n
$> aptitude install telnet<\/strong><\/pre>\nThen establish a TCP\u00a0connection to the SMTP\u00a0port:\n
$> telnet localhost smtp<\/strong>\n<\/pre>\nThe server should reply:\n
Trying 127.0.0.1...\nConnected to localhost.\nEscape character is '^]'.\n220 mailtest ESMTP Postfix (Debian\/GNU)\n<\/pre>\nGreat. Postfix is listening and wants us to speak SMTP. First we need to be friendly:\n
ehlo example.com<\/strong>\n<\/pre>\nPostfix appreciates our friendliness and tells us which features it provides:\n
250-my-new-mailserver\n250-PIPELINING\n250-SIZE 10240000\n250-VRFY\n250-ETRN\n250-ENHANCEDSTATUSCODES\n250-8BITMIME\n250 DSN\n<\/pre>\nHey, Postfix, we have a mail from steve@example.com<\/a>:\n
mail from:<\/strong>\n<\/pre>\nLooks like Postfix is happy with that because return codes that start with a ‘2’ are good news:\n
250 2.1.0 Ok\n<\/pre>\nTell Postfix who the recipient of the mail is:\n
rcpt to:<\/strong>\n<\/pre>\nPostfix accepts that:\n
250 2.1.5 Ok\n<\/pre>\nThen we are ready to send the actual mail:\n
data<\/strong>\n<\/pre>\nPostfix agrees and tells us we can send the actual mail now and end our input with a dot on an empty line:\n
354 End data with .\n<\/pre>\nOkay, type in the mail:\n\nsubject:\u4e3b\u9898\n\nfrom: \u00a0 \u4e0e\u4e0a\u9762 \u00a0mail from \u00a0\u8f93\u5165\u7684\u4e00\u6837 \u00a0 \u81ea\u5df1\u7684\u90ae\u7bb1\n\nto: \u00a0 \u00a0\u4e0e\u4e0a\u9762\u7684rctp to \u4e00\u6837\n\n\nHi John, just wanted to drop you a note. .<\/strong>\n\nPostfix tells us it has received the mail and queued under a queue ID:\n
250 2.0.0 Ok: queued as A9D64379C4\n<\/pre>\nThanks, Postfix, we are done:\n
quit<\/strong>\n<\/pre>\n<\/div>\n
\n
Checking the logs<\/h2>\nTake a look at the \/var\/log\/mail.log<\/span><\/tt> file now. You should see something similar to:\n
postfix\/smtpd[...]: connect from localhost[127.0.0.1]\npostfix\/smtpd[...]: 5FF712A6: client=localhost[127.0.0.1]\npostfix\/cleanup[...]: 5FF712A6: message-id=<...>\npostfix\/qmgr[...]: 5FF712A6: from=, size=364, nrcpt=1 (queue active)\npostfix\/pipe[...]: 5FF712A6: to=, relay=dovecot, ..., status=sent (delivered via dovecot service)\npostfix\/qmgr[...]: 5FF712A6: removed\npostfix\/smtpd[...]: disconnect from localhost[127.0.0.1]\n<\/pre>\nThe delivery has worked. Postfix has correctly determined that the destination domain is a virtual domain and forwarded the email to the ‘dovecot’ service.\n\n<\/div>\n
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Checking the user’s mailbox<\/h2>\nThe email should now be somewhere under \/var\/vmail\/example.com\/john<\/span><\/tt>. Let us take a look:\n
$> cd \/var\/vmail\/example.com\/john\/Maildir<\/strong>\n$> find<\/strong>\n.\n.\/cur\n.\/new\n.\/new\/1179521979.V801I2bbf7M15352.mailtest\n.\/tmp\n<\/pre>\nThere sits the email. Try to read the mail with the “mutt” program:\n
$> mutt -f .<\/strong>\n<\/pre>\nThe new email is shown:\n
q:Quit  d:Del  u:Undel  s:Save  m:Mail  r:Reply  g:Group  ?:Help\n   1 N   May 18 steve@example.c (0.1K)\n<\/pre>\nPress ENTER to read the email:\n
From: steve@example.com\nTo: undisclosed-recipients: ;\n\nHi John,\n\njust wanted to drop you a note.\n<\/pre>\nSo the email arrived at John’s account. Perfect. Choose ‘q’ twice to exit mutt again.\n\n<\/div>","protected":false},"excerpt":{"rendered":"
Emulating an SMTP session with Telnet Let us try to send an email to the user now. As the “exa...<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[415,414,413,416],"class_list":["post-1322","post","type-post","status-publish","format-standard","hentry","category-linux","tag-mail","tag-smtp","tag-telnet","tag-test"],"_links":{"self":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1322","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/comments?post=1322"}],"version-history":[{"count":3,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1322\/revisions"}],"predecessor-version":[{"id":1849,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/posts\/1322\/revisions\/1849"}],"wp:attachment":[{"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/media?parent=1322"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/categories?post=1322"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/nick.txtcc.com\/index.php\/wp-json\/wp\/v2\/tags?post=1322"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}