This is such an odd issue it's difficult to describe, so please bear with me.
I have a client (kirby@jibberish.com) who has purchased Hosted Exchange services from Rackspace. He has no problems sending email to anyone except ONE person (mike@foobar.com).
- kirby@jibberish.com = Rackspace Hosted Exchange
- mike@foobar.com = Microsoft 365 Hosted Exchange
- mikealias@foobar.com = an alias pointing to mike@foobar.com that we set up as a test to see if email addressed to mikealias@foobar.com from kirby@jibberish.com would be delivered to mike@foobar.com's inbox.
The facts:
- mike@foobar.com can send email to kirby@jibberish.com
- Attempts to send from kirby@jibberish.com to mike@foobar.com result in no errors, failures or NDR messages, but the message never arrives in Mike's inbox.
- mike@foobar.com has no problem receiving email from senders other than those who are sending from email domains hosted by Rackspace
- Messages sent from kirby@jibberish.com to mikealias@foobar.com GO THROUGH OK and arrive in Mike's inbox
Why would email addressed to the alias go through no-problem, but email addressed to the primary account (mike@foobar.com) seemingly vanish into the ether?