I am having trouble with one of my sendmail servers. Users are informing me about that registration emails do not arrive. The logfile claims that the message has been queued, but the queue is empty:

sudo cat /var/log/mail.log | grep email 

(with obfuscated e-mail and server adresses in this example):

Jan 6 23:33:57 fx1 sendmail[9292]: u06MXvuk009292: to=email, ctladdr=sender-email (1001/100), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=38128, relay=[] [], dsn=2.0.0, stat=Sent (u06MXv7o009293 Message accepted for delivery)

Jan 6 23:34:00 fx1 sm-mta[9295]: u06MXv7o009293: to=, delay=00:00:03, xdelay=00:00:03, mailer=esmtp, pri=128308, relay=mx3.hotmail.com. [], dsn=2.0.0, stat=Sent ( <70001a6bb8ff80254895632a2c4367fb@myhost> Queued mail for delivery)

$ mailq
> MSP Queue status...
/var/spool/mqueue-client is empty
        Total requests: 0
MTA Queue status...
        /var/spool/mqueue (1 request)
-----Q-ID----- --Size-- -----Q-Time----- ------------Sender/Recipient-----------
u04ALref018750*     184 Mon Jan  4 11:21 <[email protected]>
                 (Deferred: Connection timed out with mail.vtmail.com.)
                     <[email protected]>
        Total requests: 1

The mail.err logfile is empty.

How could I track down the problem? This is happening quite frequently.

  • As HBruijn said (in his comment that seems to be deleted now) - your server has delivered the email, so it should not be your problem. However, some servers accept mail that they then classify as spam (as opposed to just rejecting it, in which case you would know about it). So maybe there is something wrong with your server that makes other servers classify mail sent by you as spam. You could check spamhouse, verify your DNS settings (A, MX and PTR records correctly set up), verify you are not sending out spam ...
    – Isaac
    Jan 7, 2016 at 10:05
  • I converted the comment to an answer instead @Isaac :)
    – HBruijn
    Jan 7, 2016 at 10:08
  • Could you post log all entries related to u04ALref018750 (the queened message reported by mailq)? Do you get SMTP greeting message? telnet mail.vtmail.com 25
    – AnFi
    Jan 7, 2016 at 12:08

1 Answer 1


The log entry

stat=Sent ( <remote-id> Queued mail for delivery)

indicates that the remote server accepted the message. From the perspective of your SMTP server is has been delivered. It is now in the next hop towards the recipients INBOX.

What happens from there is no longer your mailserver's responsibility and neither something you can easily debug from your end, if at all. But typically the message will move through SPAM and anti-virus filters etc. before ending up either in the recipient's INBOX, Spam folder or possibly silently discarded.

Ask the recipient to check their spam folder and if found there have them forward the message headers to you is one approach. Please also read the canonical Q&A's on preventing email getting marked as spam and Fighting spam, what can I do?

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