Gmail Contacts List keeps adding back deleted recipients

A friend sends out a business-newsletter via her Gmail account. If one of her contacts askes to be removed from her list, she takes care to do so. However, when she sends out the next one, she’ll often get a ‘please remove’ notice once more from one of these removed contacts, occasionally now less politely.

I know she imported her Contacts list from her Yahoo account & I wonder if these people who are deleted from Gmail Contacts then come back via Yahoo.
Is that possible?
How to we prevent these unwanted Contacts from returing?
Thanks!

Does she have a mobile device, eg an Android phone that syncs with the gmail account and reinstates the contact?

No.

Has she deleted all emails involving that person?

Probably not.

I’d bet she has the contacts in a group, right? I have this same problem; when I created a group to include all the Girl Scout families from this year, I included several people who did not need to be on the list.

Even though I’ve removed the group association from the individual contact, if I send out something by entering “2010 Scouts” in the “to” (so it finds the group name), it includes those deleted people.

I misspelled someone’s name when adding them recently - and even though the Gmail contact is now corrected, the name comes up misspelled when I use the group name in emails. I told her she had to change her name :).

Anyway - I think gmail must somehow remember the list, unchanged, forever.

I’ve actually had to delete the list and recreate it from scratch to stop this happening.