There are 3 solutions I can think of, one of which you already have.
1. Use ~/.mailrc. This one is built into message-mode (which mu4e uses
to compose messages). All you need to do is ensure
message-mail-alias-type is set to abbrev (which I think is the defualt)
and your ready to go. Just define your aliases in ~/.mailrc e.g
alias team1 "John Smith <
jsm...@example.com>, Ronald McDonald
<
big...@fat.com>"
and then type the alias name i.e. team1 and hit tab to have it
completed.
The benefit of this approach is that mu4e contacts still works. The
drawback is there is no integration with other systems, like google
contacts, giving mobile device integration etc.
2. Use org-contacts. Setting this up is fairly straight-forward and
org-contacts is available on GNU ELPA (and MELPA I think). With this
approach, you would use a GROUP property to define different groups of
contacts. While this requires a little more manual intervention, it
would be possible to write some additional emacs lisp functions to get
exactly the behaviour you want. One advantage of this approach is that
you can set things up to have your contacts synced with other systems,
such as google contacts, making your contacts available on mobile
devices. One nice thing about it is that all your contacts are just
plain text and therefore can also be manipulated easily using various tools.
3. Use BBDB. This is a very powerful contact management database system
which has been around for decades. I used it over 20 years ago and it
was great. Extremely powerful. There is some information about
integrating with bbdb in the mu4e manual. Downside is that it can be
complicated and your contact information is in a bbdb specific database
(well really just a lisp data structure in a file).
I've used all of the above approaches in the past. Currently, I have
been using the ~/.mailrc approach because it is easy and because some
other mail clients wil also use it. However, I was using and plan to
return to using org-contacts (just haven't got around to reconfiguring
after a major system and emacs overhaul!).