How to block a user organization from emailing a group

[mcummings1]

I'm looking for the ability to block my students (in their own orginization) from emailing our group email lists.

I can't change the permissions of the group to allow emails only from users in the group becuase I have other employees that need to email the group.

Anyone have ideas on how to do this?

Thanks

[ajojose33333344]

@mcummings1  you can write a routing rule to block all incoming emails to the group mail id from the particular domain.

[zoccsi]

Hi,

Having the same problem...just can't get my head around to solve this...I think I'm overcomplicating it 😄

So...I selected the OU to apply the routing. (which members are not allowed to send emails to groups)
Add or create another rule
1. Email messages to affect - outbound and internal - sending
2. Reject the message
Show options
B. Groups
C. Envelope filter 
Only affect specific envelope senders
  - group membership - I add the group or groups whom they are not allowed to send emails to

Somehow it still not working....

Any idea why?