Weird one this, been banging my head against it since August and just a minor eureka moment now.

I had to rebuild the network and the moron that I am I set the internal domain name to be the same as our external one (school.bham.sch.uk) as it was how it was at my last place. Of course this broke Live@Edu autodiscover.

I created a CNAME record pointing autodiscover.trapper.bham.sch.uk to autodiscover.outlook.com, but it's never worked. Hence I now know our server details intimately.

Just on a fluke I created an internal SRV record tonight: _autodiscover_.tcp_10_2_443 pointing to autodiscover-s.outlook.com (apparantly the S is for the SRV connection) and it works! But it takes an age for Outlook to connect as apparantley the SRV record is the last thing it tries. Well, anything is better than nothing.

I've tried changing our CNAME to autodisc-s.outlook, but it doesn't do anything.

Either I'm a complete idiot and missed something obvious, or Birmingham is doing something funky (I'd guess option 1).

However even if no-one has a solution to the CNAME option, I thought I'd post the SRV solution as an "it-works-but-is-a-bit-crap" possibility.