Connect to a Plesk server via SSH.

Create a copy “postfix” configuration file:

# cp -a /etc/postfix/main.cf /root/backup_main.cf

Open “postfix” configuration file in a text editor, for example, “vi” editor:

# vi /etc/postfix/main.cf

Add the lines specified below to the configuration file main.cf and make sure that these lines are present only once in the file:

Note: replace example.com with required mail server name.

myhostname = example.com
smtpd_banner = $myhostname ESMTP $mail_name

Using command line tool. check “postfix” configuration syntax and restart postfix:

postfix check
(empty output - means syntax is OK)

# service postfix restart

To remove specific emails from a domain:

# postqueue -p | tail -n +2 | awk 'BEGIN { RS = "" } /@domain\.com/ { print $1 }' | tr -d '*!' | postsuper -d -

Or

# mailq | tail -n +2 | grep -v '^ *(' | awk  'BEGIN { RS = "" } { if ($8 == "USER@EXAMPLE.COM" && $9 == "") print $1 } ' | tr -d '*!' | postsuper -d -

Is it possible to change the time for mail to give up on sending (Retry) from 5 days which is right now to like 1 day or 12 hours for plesk postfix MTA?

Edit the following to /etc/postfix/main.cf near the top:

# nano /etc/postfix/main.cf
maximal_queue_lifetime = 1h
maximal_backoff_time = 15m
minimal_backoff_time = 5m
queue_run_delay = 5m

Source: http://www.postfix.org/postconf.5.html

Post fix restart produces the following

# tail -f /usr/local/psa/var/log/maillog
Mar  4 21:40:07 postfix/postfix-script[24660]: fatal: the Postfix mail system is not running
Mar  4 21:40:08 postfix/postfix-script[24731]: starting the Postfix mail system
Mar  4 21:40:08 postfix/master[24732]: fatal: bind 0.0.0.0 port 25: Address already in use

Look for multiple instances of smtp inet n – n – – smtpd and comment them out:

#smtp inet n - n - - smtpd
localhost:smtp inet n - n - - smtpd
smtp_bind_address6= -o smtp_address_preference=ipv4
#smtp inet n - n - - smtpd

Restart postfix

# service postfix restart

Mar 3 22:28:11 precisiondesigns courier-pop3s: couriertls: /usr/share/pop3d.pem: error:0906D06C:PEM routines:PEM_read_bio:no start line

http://kb.sp.parallels.com/en/122785

Error in plesk postfix email logs:

Notice: Error: EHLO not accepted from server! in /var/www/vhosts/domain.com/httpdocs/system/library/mail.php on line 237

Check postfix main and comment out non_smtpd_milters:

smtpd_milters = , inet:127.0.0.1:12768
#non_smtpd_milters = , inet:127.0.0.1:12768

Restart postfix:

# service postfix restart
Shutting down postfix:                                     [  OK  ]
Starting postfix:                                          [  OK  ]

My server is using Centos 6.5
I updated from Plesk 11.5 to 12 last week and postfix to 2.8.17.
Since then, all mails sent using the sendmail binary (notifications, mail forwards…) are being rejected with a wrong HELO hostname: localhost.
It seems that sendmail is using locahost as a HELO tag which is not accepted.

Qick Fix:

remove whole non_smtpd_milters from postfix main.cf in case you do not use commtouch.
If you would like to use commtouch then you can remove only “inet:127.0.0.1:12768” from non_smtpd_milters.
restart postfix.

Link: http://forum.sp.parallels.com/threads/postfix-mails-sent-through-sendmail-binary-are-blocked-because-of-wrong-helo.305216/

Source: http://kb.sp.parallels.com/en/115472

My server is using the Postfix mail server. For some reason, all messages it sends contain unnecessary headers, like the following:

X-No-Relay: not in my network

or

X-No-Auth: unauthenticated sender

The number of headers is multiplied by the number of message recipients, e.g., the headers of a message sent to two recipients would look like this:

X-No-Relay: not in my network
X-No-Relay: not in my network

Cause
Postfix adds those headers from these files:

# ls /var/spool/postfix/plesk/*re
/var/spool/postfix/plesk/non_auth.re
/var/spool/postfix/plesk/no_relay.re

Resolution
The issue will be fixed in a future update for which a new Knowledgebase article will be created. You may subscribe to new articles on Parallels Plesk Panel products if you wish to receive notifications about their creation.

Workaround
If you do not want messages to contain the above headers, clean (empty) these files:

/var/spool/postfix/plesk/non_auth.re
/var/spool/postfix/plesk/no_relay.re

nano /var/spool/postfix/plesk/no_relay.re

/^/ PREPEND X-No-Relay: not in my network