Stop a certain domain sending any email?

Is it possible to block one domain that I'm hosting on my ISPconfig2 system to send e-mail with postfix?

Why?? I know that it sounds stupid, but some person found a way to send email through an application that I'm hosting.

I'm working on a fix for this application, but for now the easiest (and fastest) way to fix this is to stop ANY email that is beeing send from this domain. Receiving email for this domain must still work!

Thank you for any info on this.

 

You can do this with Postfix header checks: http://www.postfix.org/header_checks.5.html

 

That looks promising.
Thank you

 

Okay.

To stop (discard) domain XYZ.TLD to send email with postfix use this in the /etc/postfix/header_checks

Code:

/^From: .*@XYZ\.TLD>/ DISCARD