Email Removing IP From Postfix SMTP Relay

This is not a default Postfix file at CentOS.

Here you go:

Add (or edit) such a line to /etc/postfix/main.cf

Code:

smtp_header_checks = pcre:/etc/postfix/anonymize_header.pcre

Add the following code to the file /etc/postfix/anonymize_header.pcre (create the file if it does not exist):

Code:

/^Received:/ IGNORE

or for more sophisticated matching for example (adapt to your needs):

Code:

if /^\s*Received:.*Authenticated sender.*\(Postfix\)/
/^\s*Received:.*Authenticated sender:(.+)/
  REPLACE Received: from localhost (localhost [127.0.0.1]) (Authenticated sender:$1
endif

/^\s*X-Enigmail/        IGNORE
/^\s*X-Mailer/          IGNORE
/^\s*X-Originating-IP/  IGNORE
/^\s*X-Forward/         IGNORE

and restart Postfix

Code:

systemctl restart postfix

 

This (and all other "Received" headers) will be matched by

Code:

/^Received:/ IGNORE

If it does not work, your Postfix does not apply header_checks to the submitted message. How does the message reach Postfix? Via SMTP (port 25) or submission (port 587) or direct handling at the server (php mail or linux mail?).

 

If you use an external mail provider (Mailgun): Almost all of them are adding the IP from where the mail was received to the headers for SPAM protection and security reasons.

I did not even know that SES allows to hide this IP.