Enable contacts management in Inventory/Mailing settings
There is currently no way to add or remove contacts manually in TSM Mail. When playing on 2 different wow accounts its impossible to add your characters from the second account to your contacts.
There is also the issue of alts that have been deleted or characters that have been name changed still appearing in the contact list and their names being auto-filled.
Just delete TSM saved data from WTF folder.
It will reset all data.
There is no way for TSM to know that you deleted an alt.
Setup account syncing and the alts magically appears ;)