Postfix Hide Client (MUA) System IP Address / Hostname

Posted on in Categories , , , , , , , , , last updated June 17, 2009

I‘ve central mail server gateway. All of our internal systems through this box. How do I remove or hide the hostnames and IP addresses of our internal systems from the messages headers before they go out to other users for security purpose?

Postfix blacklist or reject an email address

Posted on in Categories , , last updated November 6, 2007

Q. I’ve Postfix based CentOS Linux server. I need to blacklist email ID: [email protected] . How do I blacklist email address with postfix? I also have spamassassin software installed.

A. By default, the Postfix SMTP server accepts any sender address. However you can block / blacklist sender email address easily with Postfix. It has SMTP server access table.

Open /etc/postfix/sender_access file
# cd /etc/postfix
# vi sender_access

Append sender email id as follows:
[email protected] REJECT
Save and close the file. Use postmap command to create a database:
# postmap hash:sender_access
Now open main.cf and add code as follows:
smtpd_recipient_restrictions = check_sender_access hash:/etc/postfix/sender_access
Save and close the file. Restart / reload postfix MTA:
# /etc/init.d/postfix restart

You can also use spamassassin to blacklist email address. Just add to your own spamassassin configuration or to /etc/mail/spamassassin/local.cf file:
# vi /etc/mail/spamassassin/local.cf
Append blacklist as follows:
blacklist_from [email protected]
Save and close the file. Restart spamassassin:
# /etc/init.d/spamassassin restart

spamassassin will marke mail as SPAM instead of rejecting the same.