Quite often you need to be able to send email out of a device (printer, mfp, fax machine, whatever) or a program and you have to “relay” it off your email server. We all knew how to do this with our own on-premise Exchange but there seems to be some confusion about using Office 365 as a relay.
Actually, it is quite easy to set up relay email connectors in O365, this post pretty much explains it all:
A few things to note:
1) The defined process to set up an SMTP relay assumes ANONYMOUS sending from source (the email sender is NOT authenticating though O365) and sent email will NOT show up in a given user’s O365 Sent Items folder even if the user’s email address is attached to sent email as the sender. In other words, sending the email as firstname.lastname@example.org will not result in the email showing up in Joe Blog’s Outlook. This is straightforward anonymous relaying and all the cautions about anonymous relaying apply.
2) The defined process for “Client SMTP submission” WILL result in the sent emails showing up in the user’s O365 Sent Items. Note that whatever device or program is sending the email MUST be able to authenticate against O365 using TLS. There are lots of “dumb” programs and devices that can be configured to use port 587 to communicate but cannot use TLS because they don’t support it. If your program or device does not use TLS then don’t bother with this option.
3) Note that the access to the Exchange Management Portal in O365 can vary depending on the O365 account type. Small Business accounts require jumping through a few hoops to get there; the above referenced post does provide a link with guidance. Also note that O365 has already changed the look of the management interface since the above post was written. You may have to poke around a bit to find the Connectors area within the Exchange admin interface in O365. As of March 8, 2014 it is currently under Service Settings –> mail flow –> Custom mail rules –> connectors.