After a bit of to’ing and fro’ing with Zone Edit, plus the development of a script that triggers the “Send queued mail now” command for each of our domains, things seem to have settled down.
It took a few weeks after we started using the Zone Edit backup mail servers before the entries showed up in the Account Details page. During that time, we seemed to be having all sorts of problems with mails being blocked and/or disappearing. Since then, all seems fine. I’ve not been able to get an answer from Zone Edit as to whether the delay was due to their accounts system or whether it might have caused some of the problems we experienced.
There is still the issue of some mail occasionally taking a long time to get from a Zone Edit secondary to our primary mail server. Scott at APC has noted that they’ve had mails take a day. Our worst case was three days. To help avoid this, I’ve written a script that fires off every hour and triggers a “send queued mail” process on their web based mangement console.
So far, things seem to be stabilising and it looks like we’re going to be able to continue using Zone Edit as our secondary DNS and mail service. Still early days yet, but we’ll watch and see.