@mail.asana.com adding signatures to imported emails, not related to email sender

Welcome to the Asana Community Forum :wave:

This seems indeed very strange.
Is your email a user email or an alias attached to another main email?
Is this happening all the time or just one time?
Is person B in cc or in any way involved in the email you sent?

I recommend checking all of that and then reaching out to Asana support with some screenshots as they will be best equipped in assisting you to get this resolved.