Why don't my e-mails reach the recipient?

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09.04.2021 05:14

There can be many reasons why an e-mail does not reach the recipient. Usually, the sending of an e-mail is documented in the log files of your server under /var/log.

The following excerpt from /var/log/mail.info shows the successful sending of an e-mail from test@myloc.de to support@zkm.fastit.net

Apr 5 10:34:22 testserver sendmail<29927>: l358XSQG028484: to=support@myloc.de, ctladdr=test@myloc.de (0/0), delay=00:00:13, xdelay=00:00:04, mailer=local, pri=30446, dsn=2.0.0, stat=Sent

The status stat=Relaying denied would indicate that you are trying to send this e-mail without prior authentication. However, your e-mail client should also display this as an error message.

The status Sent in the above example means that the e-mail has been successfully delivered. If the e-mail does not arrive in this case, the error is on the recipient's side.

Receiving server reports error

If the receiving server sends back a message (e-mails from mailer Deamon), it is either delivered to the sender or ends up in the root mailbox under /var/mail/root.

Mail is classified as SPAM

If your mail is classified as spam, there is normally no notification. The following actions can happen here.

  1. The e-mail ends up in the recipient's spam folder.

    In this case, the recipient can move the e-mail to his/her inbox by simply copying/moving it.

  2. The e-mail is discarded

    In this case, the e-mail is lost and may have to be resent.

 Why the e-mail is classified as spam depends, among other things, on the configuration of the mail server. There are several approaches:

The most common are the evaluation of the DNS entries, in particular the RDNS address of the server is compared with the name of the mail server, as well as the comparison with so-called blacklists. You can check whether your server is listed on these blacklists, for example, at http://mxtoolbox.com under the item Blacklist.

Your server uses more than one IP address

In this case, your SMTP server is not bound to a fixed IP address and chooses an address at random. This then leads to problems when resolving the RDNS entry, which is usually no longer compatible with the name of the mail server if the main IP is not used.

You can bind Postfix to a fixed IP with the following two lines:
postconf -e "inet_interfaces = 192.168.178.1"
/etc/init.d/postfix restart

For Qmail, you can set the outgoing IP as follows:
echo "192.168.178.1" > /var/qmail/control/outgoingip
/etc/init.d/qmail restart


Replace 192.168.178.1 with the IP you want your mail server to use.

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