Very latest discourse.
Discourse adds an entry for when email groups:
@carlokok INVITED @SUPPORT2 4 HOURS AGO
and does an explicit, empty email for that:
Update: Looks like it adds a staged user for the target address (support2) of a gruop and then sends an empty notification about that.
Where do these staged users live? Can they be viewed in the admin User list?
I am testing this out too.
They’re in the users list, but they show as light gray.
What version are you running? This was fixed by
https://github.com/discourse/discourse/commit/61cc776fdd08bc692ea2391a10d84c06c096906a
@zogstrip: https://github.com/discourse/discourse/commit/665fc44741e6f0a7717bd7941648618fce3782cc
Note that there are two issues here:
Just pushed a fix about that specific issue 
https://github.com/discourse/discourse/commit/735017dd9fb846a2b5418935355f1f9fda493b41
Also, you might want to disable emails (both “Send me an email when someone messages me” and “Send me an email when someone quotes me, replies to my post, mentions my @username, or invites me to a topic”) for all the staged users with email matching a group’s incoming email. I might make this automatic but for now a manual workaround is enough.
Cool. Ofc this fix will hide the notification issue.
Btw: really impressed with this feature. Reported a few issues but really liking it so far.
Got a bunch of “Carlo_Kok” accounts now for email addresses like:
3d6bfe09ec4c581e1d252a331982@talk.remobjects.com
(talk.remobjects.com is my incoming email domain). Will this fix that too?
What does your “reply_by_email_address” setting look like?
If it’s %{reply_key}@talk.remobjects.com then yes
thanks. Upgrading now 
I think I understand now. I email to sales@remobjects.com which is an alias to something@talk.remobjects.com. The fix seems to work for the last one directly, but not the first one, which is the incoming address for the group.
I actually did make it automatic because it wasn’t that hard and was annoying the hell out of me 
