I recently converted a user's mailbox, email@example.com with name Mike Smith*, to a shared mailbox firstname.lastname@example.org with name Info_Example. I was informed by one of the users of this new, shared mailbox, that one of their sent emails was given `From: Mike Smith`. Almost every other recently sent email shows the expected `From: Info`. I am stymied. The email chain in question appears to have begun after the shared mailbox creation. I'm not sure where to check beyond the Shared Mailboxes section of the Admin Center. Any ideas?
*I'm not sure if 'info' was always their email address, or if they also had a email@example.com email address, or if 'mike' was renamed to 'info' at one point, or something else.