Disabled Plesk mail and Specify External Mail Server

Hi there,

I have disabled my Plesk mail and specified an external SMTP mail server for Plesk. I am using Microsoft office 365 for the mail. However, I can see that the mail isn't working. Please see this log entry:

Nov 28 03:24:48 panel01 msmtp: host=smtp.office365.com tls=on auth=on user=[My Office 365 User] from=root@[My Plesk URL] recipients=[My E-Mail] smtpstatus=550 smtpmsg='550 5.7.60 SMTP; Client does not have permissions to send as this sender' errormsg='the server did not accept...

Disabled Plesk mail and Specify External Mail Server