Set distribution group to reject all e-mails from a certain domain

We have been bought out buy another company and are in the process of moving distribution groups shared inboxes etc. over to the new companies domain.

We have one distribution group for our accounts team where they receive various e-mails from external sources, some of which are still linked to the accounts of our 'old' company which has not been wound up yet. For audit purposes we need this external company to continue to send these notifications to our [email protected] as some of them also send information to the new company on their @domain and we don't want the information to become mixed.

However we have been asked by the board to try and find a way of making sure that all staff members start using the new distribution groups for internal work.

My question is there a way to set a distribution group to reject all e-mails from a specific domain so that they get a bounce back and then have to make sure to use the new group on the new domain?

Kind regards

Solution 1:

My question is there a way to set a distribution group to reject all e-mails from a specific domain so that they get a bounce back and then have to make sure to use the new group on the new domain?

You could create the following Transport Rule in the EAC to reject these emails which are sent from a specific domain to the old distribution group:

After that, if you send emails to the old group with a mailbox which is in a specific domain, these emails will be blocked with an explanation(If you send an email to one member of the group, the email will not be blocked.):