Mail forwarding does not work in Plesk for Linux: 550-Verification failed for SRS0

Stefan Yakubov

Updated November 20, 2023 08:32

kb: technical ABT: Group B

Applicable to:

Mail forwarding fails, error in /var/log/maillog

CONFIG_TEXT: plesk postfix/smtp[8055]: AABBCCDD11: to=<sender@example.com>, relay=<relay_host_hostname>[203.0.113.2]:587, delay=0.16, delays=0.02/0.02/0.08/0.03, dsn=5.0.0, status=bounced (host <relay_host_hostname>[203.0.113.2] said: 550-Verification failed for <SRS0=p0uz=4E=example.com=sender@example2.com> 550-Previous (cached) callout verification failure 550 Invalid sender <SRS0=p0uz=4E=example.com=sender@example2.com> (in reply to MAIL FROM command)

Sender Rewriting Scheme (SRS) support is enabled in Plesk, however it is not supported on the relay host.

Recommended solution is to enable acceptance of SRS for emails from Plesk on the relay host.

Disabling SRS support in Plesk (not recommended).

Warning: This solution will make the environment less secure because the sender's email policy will be ignored.

In case it is not possible to enable SRS on the relay host, SRS can be disabled in Plesk following the next steps:

Connect to the server via SSH
Open the /etc/postfix/master.cf file and find the following line:

CONFIG_TEXT: plesk_virtual unix - n n - - pipe flags=DORhu user=popuser:popuser argv=/usr/lib64/plesk-9.0/postfix-local -f ${sender} -d ${recipient} -p /var/qmail/mailnames
Add -s to the end of the line:

CONFIG_TEXT: plesk_virtual unix - n n - - pipe flags=DORhu user=popuser:popuser argv=/usr/lib64/plesk-9.0/postfix-local -f ${sender} -d ${recipient} -p /var/qmail/mailnames -s
Restart the postfixservice:

# systemctl restart postfix