I was asked to post this as a new thread rather than replying to ALL the ongoing threads concerning the same issue.  This has been an ongoing issue since the switchover from hotmail to outlook.com.  It has not been addressed by microsoft or the outlook team.  By the way outlook stinks and you have continued to make it more inconvenient for users, as you have removed "popular  and convenient features."  I have sent feedback but to no avail.  Now to the problem at hand.  I am having this same issue with more than one group.  I have removed some members from groups that I created in hotmail.  They are not removed.  They do not show up in the group member list, nor in the group email list when expanded in the "to" address bar.  But once the email is sent and I check the recipients in the sent email and they are listed as receiving the email.  I sent screenshots to a moderator, who never responded.  I will not rebuild my group lists, as one moderator suggested.  The problem is still ongoing, I sent an email today, and those that I removed MONTHS ago are still on the recipients' list.