The account is installed by a strange gmail

Le_nhi

my account has got weird gmail and i can't remove it from my account

obtainer

your username at mail.com right?

If that's the case, try registering for one at mail.com
It should be a simple fix if the account isn't taken.

If you still need help the forum email might just be a visual glitch but the email your account is tied to can be changed regardless here is the physical way to do it:

Go to settings in the BG app > Tap on "Security" option > Tap on Safety Settings > and you should see safety mailbox. There you have to either:

add your Gmail/email
un-bind it and add a new one (if needed)

I hope this helps!