Bounce mail if subject does not contain certain words

[harripiili]

I need to implement a message rule for one email account where messages are bounced with customized message if subject does not contain certain keywords.

I think that proxmox could handle all the other parts of this requirement, but I cannot find a way to create a negative filter in What rule.

I'm trying to create a What rule that would notice if subject does not contain text '[('

Would there be a way to do this OOTB or shall I start looking into custom spamassassin rules.

 

[tom]

I need to implement a message rule for one email account where messages are bounced with customized message if subject does not contain certain keywords.

I think that proxmox could handle all the other parts of this requirement, but I cannot find a way to create a negative filter in What rule.

I'm trying to create a What rule that would notice if subject does not contain text '[('

Would there be a way to do this OOTB or shall I start looking into custom spamassassin rules.

I see no way how to do this.