Desperately seeking help with the SendMail function. I have been using SendMail for a few years to send batch mailings of data, grade reports, tests, feedback, etc., directly to my students. It has worked flawlessly until yesterday when testing it for this semester and receiving the error message: Login credentials were denied by the server "outlook.office365.com". My mail settings are these:

MailSettings -> <|"FromName" -> "My Name Here", 
  "FromAddress" -> "myWorkEmail@domain.ca", 
  "Server" -> "outlook.office365.com", "PortNumber" -> 587, 
  "EncryptionProtocol" -> "StartTLS", 
  "UserName" -> "myWorkEmail@domain.ca", 
  "Password" -> "myPassWord"|>

I don't know whether there have been changes made to the SendMail function or the server at my university (IT has not been much help in that regard). I've tried to change various options in MailSettings but nothing has worked. I'm using a Mac and Apple's Mail client.

Any help would be much appreciated.

Gregory