Using Outlook for Android for personal email and calendar management
Hello,
Any chance you removed one of the following alias?
outlook.com hotmail.com live.com msn.com
If so, once it is removed from a Microsoft account as an alias, that alias is gone permanently.
Microsoft doesn't reuse its own email address, so it cannot be added to created as alias for another Microsoft account.
Microsoft explains it here: https://support.microsoft.com/office/add-or-remove-an-email-alias-in-outlook-com-459b1989-356d-40fa-a689-8f285b13f1f2 Under the section "Remove an email address", it says: "Are you sure? If you remove an alias that's an email address from a Microsoft domain (like @hotmail.com, @live.com, @outlook.com, or @msn.com), you're permanently deleting the alias and it can't be associated with any Microsoft account again."