Mail adopts group name for "To" & "From"

Question

My wife's Mail app (on MBA running Yosemite) adopts one of her Contacts group names  for the "To" with incoming mail and for the "From" with outgoing mail i.e., her name or email address don't display, the group name displays. I looked at her contacts and the group and saw that she had herself in the group so I took her out but to no avail. I then clicked on the drop down of the group name displayed in the "To" and selected the "Remove from ..." Option. But to no avail.
Any ideas as to what is causing this would be appreciated.

Answer 1

Does the Previous Recipients List have anything to do with this? If she sends an email to a group (her book group) in which she is also listed, would Mail then display the group name in the "TO" instead of my wife's name? Or if the email is from someone on the group list, display the group name instead of the sender's name?
I'm just apply some possible logic as to how this app might be wired wrong...I've seen the posting on grouping unrelated emails in "conversations" which seems to me to be a coding bug.
Manage email addresses in the Previous Recipients list
Mail keeps a list of the email addresses you send messages to, and uses the list to suggest or complete addresses for you when you send email. You can delete obsolete or incorrect addresses from the list so Mail stops suggesting them, and use the list to quickly see or add people in the Contacts app.
Choose Window > Previous Recipients.
Do any of the following:
Sort the list: Click a column header.
Search for a name: Enter the name in the search field.
Show recipients in Contacts: Double-click a name. A card icon precedes names that are already in Contacts.
Add recipients to Contacts: Select a name, then click Add to Contacts.
Remove recipients from the list: Select one or more names, then click Remove From List.