Mark Svancarek via UA-EAI writes:
> I have also tried using gmail IMAP a few times with my xgenplus
> addresses, and couldn't get it to work with an EAI address. 
> What is the "after authentication" process I should be using?

You as user cannot do that.

After authentication, the IMAP server declares which extensions it
supports. The IMAP client may then use those, or declare that the IMAP
server should start using some. Your IMAP client should issue that
declaration ("… ENABLE … UTF8=ACCEPT …").

If your client doesn't declare that, and this isn't something users can
affect, then the IMAP server doesn't have permission to send the client EAI
addresses (they would be syntax errors) in messages, and will instead carry
out some downgrade process.

Arnt