Stop certain teams accounts from appearing in searches

[Fredkazi]

Hope I can get some guidance for an issue we have. 

So we have a Microsoft 365 tenant with two domains; domainA.com and domainB.com

Some users have email accounts for both domains 

These users only use one Teams account, domainA.com

The issue is that other users in the organization  keep mistakenly sending messages to the domainB.com account on Teams. This happens because when you search the users name both appear. 

Is there a way I can perhaps just block users from being able to send messages to those inactive teams accounts of domainB.com?

[#2]

There is, via Information barriers: https://docs.microsoft.com/en-us/microsoftteams/information-barriers-in-teams

But apart from the licensing requirements, which might be prohibitive, make sure this will not affect "regular" communication between users.