[Wylug-help] Office 365 and Exim sharing a domain

[Gary Stainburn]

Hi folks.

Appologies for the O.T. post but either my head or my wall will probably give 
in soon.

I've got a traditional email setup with a number of Exim / Dovecot servers 
dotted around my network, all working together and working well.

All users stare the one domain, with lookups using local copies of a 
Postgresql database to route users to their *local* server.

I am now trying to set up an Office 365 pilot which will host a small number 
of trial users.  My problem is that I cannot get O365 to share a domain. By 
using the routing abilities of EXIM I can get email into the O365 user's 
mailbox, but I have not been able to get the O365 users to be able to send 
out emails using the ringways.co.uk.  It appears that if i want to do that, I 
have to add the while domain to the pilot at which point I cannot route 
emails from the pilot users to the users on the existing set-up.

Does anyone know how I can set up the config so that O365 will allow outgoing 
emails to be from my domain and not the onmicrosoft.com domain?

There are many articles online regarding configuring hybrid systems but these 
all require MS Exchange as the on-premis server, not EXIM.
-- 
Gary Stainburn
Group I.T. Manager
Ringways Garages
http://www.ringways.co.uk