ResolutionIf you are able to send mail from a mail client software or using PHP scripts without any errors, but it is never delivered to the destination mailbox, perform the following steps to find the problem:
- First, make sure that Qmail is running on the server using the $PRODUCT_RC_D/qmail status or ps ax | grep qmail-send | grep -v grep command. If the "qmail-send" process is not running, then mail is not processed at all. Try to restart Qmail.
- When mail is sent from a PHP script, PHP usually uses the "sendmail" binary. Plesk has its own sendmail wrapper, so /usr/sbin/sendmail should be a symbolic link that points to "$QMAIL_ROOT_D/bin/sendmail"; check that this is the case.
- Mail delivery can be seriously delayed if there are too many messages in the queue; check how many messages are in the Qmail queue using article 766.
- Make sure that /var/qmail/bin/qmail-queue* files have the right permissions and ownerships; see article 836.
- Qmail writes very detailed logs, so you can open $PRODUCT_ROOT_D/var/log/maillog and then try to send mail again and look for errors. A list of errors and their descriptions can be found in article 1398.