This is intended behaviour; it is not a bug.
The current version of Mailman is much easier to manage for the individual subscriber: all of their subscriptions show up on one list, they can manage their subscriptions easily, and so on. In order for this subscriber feature to work, it means that there is a single list of all subscribers. Thus, if someone has already subscribed to one Mailman mailing list, their email address will show up in the same manner in all lists, most frequently looking like "
joe@whatever.com": When that person is subscribed to a new list, their email address will show up in that manner, no matter how the listadmin enters it when subscribing the user.
It's a bit more of a nuisance for listadmins who had previously used the user subscription function to make some kind of annotation about the user. I asked about this very early after the changeover because we used to annotate subscribers to the Checkuser-L mailing list with the name of their project, but could no longer do it. This was verified by the developers who installed the upgraded version.
It's a minor inconvenience for listadmins, but a significant feature for subscribers to multiple lists.
Risker/Anne
(Listadmin for multiple mailing lists)