How to change Postfix SMTP banner

How to change SMTP banner in Postfix In a postfix, by default, SMTP banner set as follow:

myhostname = domain.tld

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)

SMTP banner can be changed either via modifying myhostname or smtpd_banner variables definition.

# postconf "myhostname = domain.tld"

OR

# postconf "smtpd_banner = domain.tld ESMTP"

Alternatively, open the /etc/postfix/main.cf file with your favorite text editor:

vi /etc/postfix/main.cf

Then look for the lines above and edit as necessary. Once done, quit the editor and restart the postfix service:

# service postfix restart

Then test the SMTP banner using our DNS Tool here - https://dnstool.webcore.cloud/smtp