Very strange behaviour working fine one day and not another. No patches installed from when it worked to when it didn't.
SMTP receive connectors are also refusing connections now.
No issues that I can tell with DNS or AD and there is nothing glaringly obvious in the event logs. The only thing I have found is that when mail is "Sent" from the outlook client or OWA it gets put in to drafts and not outbox and nothing in the submission queues.
We can't even mail internally which is strange!
Any ideas anyone?
any help greatly appreciated.
This is a pretty common problem that seems to be related (in most cases, anyway) to problems with DNS configuration. Make sure that Exchange is using the DNS servers you want it to, which may or may not be the same as the ones you have bound to the NIC in that server. http://thoughtsofanidlemind.com/2013/03/25/exchange-2013-dns-stuck-messages/ has a pretty good explanation of why this issue occurs and how to fix it.