I had to delete and re-add my BT email account in Outlook for Android after having to change my password [it's the only way to do it] and now sent emails say they are from "derived from envelope by postmaster@btinternet.com <email@btinternet.com>" . The display name is not blank and other email apps are working correctly. Any help gratefully received, thank you.
Uninstall Outlook and install Blue Mail