[...] Yup. It’s the anti-virus software provided by an ISP. In this particular case it’s Shaw. Man, I hate Shaw. [...]

[...] I’ve had a very bad experience working with Shaw so  it was very nice working with good experience people at Telus. So thank to Darren Entwhistle [...]

We finally fixed it by telling Shaw to nuke the mailboxes. That is to say, even though the old Shaw boxes were disabled, they were still grabbing mail. So we insisted on having them deleted, and finally the mail got routed out of the shaw portion of the internet and to the proper mailboxes at radiant. The procedure went as follows:
1. Log onto Shaw mailservers one last time and scoop up the mail.
2. Phone 1st tier support and them to blow away the mailboxes.
3. Wait a few hours and test from a known problem email address.
4. You might have to phone Shaw again in a few hours and ask them to escalate the call to their DNS people (second tier) to fix the problem once and for all.

But you have to blow away your mailboxes, otherwise you are stuck at 1st tier forever, with Shaw support just shrugging their shoulders and passing you around like a hot potato.

We have exactly the same problem as you. Has your problem been resolved? if so, how did you get it resolved. If not, I would like to contact you for further info and possible action.

DJ,

Have you used a tool like Dig, http://networking.ringofsaturn.com/Tools/dig.php, to check your client’s zone records in the DNS? If they’re not what you expect, that leads to the next question…

Who hosts your name servers?

If the answer is Shaw, consider migrating to something good and cheap like easydns.com that you can manage yourself and not have to wait for people to do it while executing the expert yoga positions you allege they can pull off, which must take a lot of concentration.

Of course, this requires your client having control over their root domain registration.

If you’re lucky, your client registered their domain through something like webnames.ca and you can get the admin account and make the nameserver change yourself.

The process goes like this:

1) set up an easydns.com account (or whatever).
2) copy your zone files over to the new name servers
3) test them to make sure they’re answering correctly when you query them.
4) change your root domain record to point to the new name servers
5) forgive Shaw – it’s good for your soul

–E

“Launch the nuke into the kill zone, NOW!”