Using Office 365 as an email Smart Host

Just thought I would post on how to use Office 365 for all those pesky printers/scanners/network equipment/server that need to send email but do not like using authentication for some reason with Office 365 or if you simply do not want to pay for a mailbox that this equipment uses.

All this info can be found here: http://technet.microsoft.com/en-us/library/dn554323%28v=exchg.150%29.aspx

But to sum it up:

  1. Login to the Exchange Management Center
  2. Go to mail flow --> connectors
  3. Add a new inbound connector
  4. Name: Outbound Relay
  5. Select “enable inbound connector”
  6. Select “on-premises” for the connector type
  7. Select “Opportunistic TLS”
  8. Select “restrict domains by IP address”
  9. Add a "*" for sender domains
  10. Add the Internet IP for all the systems for the “Sender IP address”
  11. Nothing in the associated accepted domains.

After the connector is setup you need to find the MX record that Office 365 recommends.  This can be found in the Office 365 admin center under domains by clicking on view DNS settings.

This will be the SMTP server you want to use for all your systems.

One thing to note is that you will need to have static IPs for this to work.  This setup will bypass all authentication needed by Office 365 to send message as it locks it down by IP.

For the sites of mine that do not have static IPs for the internet I setup a windows SMTP server that then relays off to Office 365.

Guide: http://technet.microsoft.com/en-us/library/dn592151%28v=exchg.150%29.aspx

This works like a charm.  This way all email is handled by Office 365 and there will be no delays as some ISP SMTP servers tend to have.

Hope this helps someone.


  • Thank you for this brief lineup. Got it working in 5 mins! - stevecharon 8 years ago
    • Glad to help. - smalls 8 years ago
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