Outgoing filter - spam - aren't those notifications dangerous?

[Miktash]

If we configure proxmox mail gateway to filter outgoing spam it will effectively filter spam and virusses.
But it will also send notifications to both the sender and the admin in case an email gets blocked.

This behaviour is fine for normal users but what happens if an account of one of our users gets hacked?

Those hackers can try to send spam email and proxmox mail gateway will block them and while doing som maybe send like thousand notifications to admin and sender.

The problem is that those hackers can forge the from address and proxmox will be sending the notifaction to the forged address. This can be an issue and potentially get the mx server blacklisted ?

Is there a way to block outgoing email for unknown sender domains?

 

[Stoiko Ivanov]

But it will also send notifications to both the sender and the admin in case an email gets blocked.

This is configurable in the rule-system

IIRC the notifications get sent to the envelop-sender (i.e. not the From header) - if they hack an account that would result in that account getting the notifications - but as said you can remove the 'Notify Sender' action from the rule.

Hope this helps!

 

[Miktash]

Some of our internal systems are webservers so a hacker can certainly forge the envelope-sender too.

Disabling the "Notify Sender" action is an option but then nobody gets a notification, not even if the system incorrectly thinks an outgoing email is spam. That's why it's probably not a good idea to disable notifications.