Change suggested Emails

[TvRi]

Really often Gboard suggests email addresses when I am starting to type my name. Unfortunately it is never proposing my Yahoo email (name_secondname@yahoo.de). I have no idea how to add this email address so that it is proposed next time? Adding it manually to the dictionary in Settings did not help.
Is it possible that there is a problem with the underline in my email?

Thanks!

 

[Hadron]

In my experience keyboards like Swiftkey and GBoard learn email addresses that I frequently enter. I don't know whether telling it to forget these other addresses would help it to suggest the correct one? Of course you may want it to remember the others as well.

I wouldn't have thought that an underscore would stop it, but as none of my addresses (indeed nothing I type often) has one of those I've no experience of whether it does or not.

 

[TvRi]

I have tried to forget the other emails just to test it.
Unfortunately it really looks like the underline is the reason why words or emails are not saved to the dictionary.