Replies not working as expected

Every time a new response is added to an email thread, it adds another “RE” then a number to the subject. So instead of keeping it RE: checking in, it will say RE (2): Checking In, RE: RE (3) Checking in and so on which makes it very difficult to group by subject line. All the RE’s are grouped together first, followed by all the RE: RE (2)'s, then the RE RE(3)'s and so on.

You can change the behavior of this in Tools->Settings->Mail->Compose

Thank you! I changed the settings from RE: (3) to just RE and it seems to have done the trick.