When replying to issue by email, email address in comment gets mention-ified (BB-7292)
when I reply to bugs via my gmx.net email account, then in the bug tracker my email domain becomes a link to the profile of the user "Graham Max" (with whom I never had anything to do). I suppose you auto-expand Graham Max' username (gmx) automatically. This is quite irritating.
I don't know if you have access to your customers bug tracker, but an example would be here: