We have various clients using office 365 for their email. Strangely enough all of them are having intermitting issues sending to customer(s) who use mdaemon mail server. About 1 in every 3 emails sent to a mdaemon customer are getting terminated before the message can complete. We have checked the logs, firewalls etc and there is no pattern except for it except being customers of office 365 sending to a mdaemon mail server customer. To confirm all logs show these messages arriving and passing spam / av filters, its just at the end before mdaemon saves the message you get a socket error.
Can you help us with this issue as we are have great difficulty getting support from office 365 ? Please see failure below:
Fri 2013-10-11 15:26:51: Socket error sending response to DATA
Fri 2013-10-11 15:26:51: * Winsock Error 10054 Connection was reset by the other side!
Fri 2013-10-11 15:26:51: SMTP session terminated (Bytes in/out: 84153/404)
Fri 2013-10-11 15:26:51: ----------