My 'Microsoft 365 for Business' account contains two domains. A user has a primary email address and an alias to reflect the second domain. In the desktop Outlook app mail is received from both domains into the primary domains inbox (but can be identified by the 'To' address) However it appears there is no way to send mail from the alias address as it does not appear in the 'From' address options. It can of course be typed in manually using the 'other address' option but the recipient still sees it as 'From' the primary address not the alias. Can anyone give me a clue as to how I would send from the alias in Outlook desktop, or confirm this is just not possible?