IIRC, it¡¯s controlled mainly by the user, who change their email address set up aliases, etc. I also know groups.io isn¡¯t happy with multiple user¡¯s & emails in different browsers. It¡¯s happiest with a single login, multiple groups and possibly usernames.
I have a drop-down for selecting the active group.
?
Cheers,
Dave F.
Dave Farrington