We have a Sendio SPAM filter and starting a week ago we are unable to send or receive email to or from customers of Office 365, Hot mail or Exchange Online Protection. If we remove Sendio and point messages directly into and out of our Exchange 2010 server, mail will flow to any address as it did before.
The message generated by Sendio:
We were unable to connect to the destination server(s):
On Tue Apr 19 at 09:17 CDT, Tried to deliver, but not ready On Tue Apr 19 at 08:22 CDT, TLS connect failed: timed out; connected to 207.46.163.247.
One other interesting thing to note is if we normalize the SPAM filter and change the route out to a different ISP, the messages will work.
It is as though in combination with original ISP and SPAM filter we have failures to Microsoft Office365, EOP and Hotmail customers.