Microsoft Exchange account won't send mail in Apple Mail

catservants wrote:

I have three Exchange accounts on my MacBook Air in Apple Mail. In two of the accounts, mail will not send. I try to go to Preferences --> Accounts --> Server Settings, but there's no way to do anything with Exchange accounts. And for the one that does work, it doesn't appear in the Edit SMTP server list, but in the Server Settings tab it shows the name of the email account, followed by [Exchange]. On the other two, for Outgoing Mail Server it says None.

I found in another discussion to try going to the Office 365 Admin Panel and unchecking some boxes and checking them again. After doing that, eventually that Exchange account showed up in the SMTP Outgoing Mail Server list for the account I did this with, so I added that to the Outgoing Server. However, when I try to send a message, Apple Mail says there is no outgoing server, and the Exchange server is not in the list to choose from on the "can't send message" server list. So, I still cannot send a message.

MacBook Air 2017 on 10.15

You can try deleting and reinstalling the account.

IF that doesn't work ask Microsoft on what to do https://support.microsoft.com/en-us