Adding @Kevin Bendixen @Milan @Nathan Sudds in case they can advise with this  

Hi @Steve Ervin, apologies for being late with the reply, but here are my thoughts.

1. You do not want to sync test accounts to Intercom - if you are syncing via Intercom API simply ask devs to have a logic that says whenever there is a user in your system with @testdomain.com as email address, simply do not sync it.
2. But I understand sometimes you actually want to test the whole customer journey and you want test users in Intercom - then I’d say make sure that in every Series, Email, Chat, whatever feature, you simply exclude those who have email ending with @testdomain.com. Sometimes I build complex Series and I want to test them and I do that in production where I set entry rule to accept only my test accounts and set it live. Once I’m ok with the test, I can just remove that part of the rule and let everyone in, but than I have test accounts messing up the metric - so what I do is that then I duplicate the Series and launch that duplicate instead of the original. Original can stay for further testing if needed.