Hi all,
having a nightmare with this.
My exchange is sending some email fine, but some will just not send. The ones that will not send first of all get delayed then fail with the following...
#550 4.4.7 QUEUE.Expired; message expired ##
I noticed there was a broken NIC team on the exchange which I have resolved now.
I also noticed there was a reverse lookup zone for an invalid subnet which I have resolved now.
I also noticed there was no SPF record as the send connector is sending using DNS.
I also noticed the top two forwarders in DNS were invalid, I removed these and added OpenDNS and googleDNS forwarders.
Yet mail is still failing to send.
Am I missing something? Is there another DNS record in addition to the MX and the SPF that I need?
Thanks in advance.