Is it possible to have different SMTP banners for different IP addresses on the Plesk server?

Vladimir Levchuk

Updated March 11, 2025 03:48

kb: how-to Plesk for Linux Plesk Obsidian for Linux ABT: Group A

Applicable to:

Plesk for Linux

Question

Is it possible to have different SMTP banners for different IP addresses on the Plesk server?

Each IP address has different PTR records, and they do not match SMTP banners.

Answer

There is no such functionality in Plesk yet. Vote for this feature at our User Voice portal.

Workaround (click to expand)

To set up SMTP banner for outgoing traffic define smtp_helo_name for specific IP address in /etc/postfix/master.cf configuration file:

CONFIG_TEXT: plesk-203.0.113.2- unix - n n - - smtp -o smtp_helo_name=example2.com -o smtp_bind_address=203.0.113.2 -o smtp_bind_address6= -o smtp_address_preference=ipv4
To set up SMTP banner for incoming traffic do the following in /etc/postfix/master.cf configuration file:

Comment out:

CONFIG_TEXT: smtp inet n - n - - smtpd
Add one entry per address:

CONFIG_TEXT: 127.0.0.1:smtp inet n - n - - smtpd -o smtp_helo_name=localhost -o smtp_bind_address=127.0.0.1 -o myhostname=localhost
x.x.x.x:smtp inet n - n - - smtpd -o smtp_helo_name=mail.domain_x.com -o smtp_bind_address= x.x.x.x -o myhostname=mail.domain_x.com
y.y.y.y:smtp inet n - n - - smtpd -o smtp_helo_name=mail.domain_y.com -o smtp_bind_address=y.y.y.y -o myhostname=mail.domain_y.com

Note: the file may be overwritten during Plesk updates, back it up.

In some cases, it might be required to use -o inet_protocols=ipv4 flag in the lines (like below). However, in majority of cases it is not required. Check the postfix/inet_protocols for more info.