Finding specific domain in my instance

[matthardy]

We recently had to change our domain for our current instance due to some changes in policies on what we can use to send out third-party software. And I was wondering if there is a way to get an alert or a report on everytime that old domain is used for an email so that we can find it and change it.

[SanfordWhiteman · Accepted solution]

1. Deliberately break the DKIM TXT record for that domain (the m1 DKIM selector).
2. Make sure that domain has a DMARC entry that requires a DKIM signature.
3. Look at the DKIM reports that come in from that domain, which will note the failed attempts.