Some email not sending micoma 4 years ago updated 4 years ago Answered We have two domains - sslcnow and disabilitydatamanager (DDM). All sslcnow email is directed by Microsoft 365 (i think). I set up email accounts for DDM. From the webmail an email sent to [email protected] was bounced with this error: This message was created automatically by mail delivery software.A message that you sent could not be delivered to one or more of itsrecipients. This is a permanent error. The following address(es) failed: [email protected] No Such User Here but another email sent to a hotmail account went thru. sslcnow.com is the default domain in 365. We have no other issues with sslcnow email.