E-Mail Server Configuration For Dummies

Well; I feel like a wally.

SmartData‘s taking on a new client for a content-managed web site, web and e-mail hosting. In anticipation of the domain transfer going through without a hitch, I reconfigured our web and e-mail servers to already be ready to accept connections to their “new” web site and for e-mails to come through. This is a wise move, because not all of the computers on the internet appreciate moving domains at the same time, and so for a day or so, e-mails will be going to both the old e-mail server and the new one: the new one needs to be ready to catch these before the first computers start sending e-mail to it.

Unfortunatley, I underestimated the intelligence of the configuration tools and the anti-spam mechanisms of our e-mail server software.

So, I send an e-mail to our client, who we’ll call bob@our-new-client.com, from my @smartdata.co.uk address. It goes out through our mail server. This is where it all goes wrong. Normally what our mail server would do would be to look up where on the internet our-new-client.com’s e-mail is kept, connect to there, and deliver it, but our mail server is a little bit lazier than that. It thought to itself, “Hey, I am the e-mail server for our-new-client.com: I know this, because I’ve been configured to accept mail for them,” and so it happily filed all my mail to bob@our-new-client.com… on their new mail server.

And then the news came through that there were complications in the domain name transfer, and it would be a few more days before they could easily pick up said mail. So, I’ve happily e-mailed them a request for their deposit on their hosting package with us, and they’re wondering why we haven’t asked for it yet, so they e-mail us. Here’s what happens:

Their e-mail server contacts our e-mail server and says “I am our-new-client.com, and I have an e-mail for dans-real-address-goes-here@smartdata.co.uk.”
And our mail server thinks “Hang on, this server is pretending to be our-new-client.com, but I know that I am responsible for our-new-client.com’s e-mail. This must be a filthy spammer trick.”
But our mail server was configured by me, so it’s a little devious. It responds (to the real our-new-client.com mail server): “Okay, I believe you, give the the e-mail.” (so those filthy spammers have no idea whether their mail got through or not) Then it shreds the e-mail and buries it in virtual concrete.

And so, for the latter half of this week, neither our newest client or us have been able to e-mail one another, and it’s only today that I’ve noticed.

Bugger.

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