Email Migration Pain
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I’m in the process of moving my email for the greghughes.net domain to a new mail server, and I’ve realized - once again - just how complicated spammers have made our lives. Especially from a technical standpoint.
PTR records in DNS and RBL records on services that no one ever heard of and which have no set rules to determine what gets on the list or how to engage them in getting off a list. What a mess. Luckily I am not on any RBL lists (with the exception of one idiotic one that everyone seems to be on, and which I certainly hope no one ever uses). But I have friends and acquaintances who have been in that boat before and it’s not fun.
But the biggest pain with moving a mail server has to be DNS propagation and the wrenches people throw into it. Enough time has passed that all locations should be pointing to the new mail server, because the old DNS records have expired. Yet there are a significant number of (large and prominent) email and Internet service providers (including my own) that are apparently caching longer than the record provides. Fun. That means I am checking two mail servers (and that’s a bit of a challenge, let me tell you), and that I cannot send email to pretty much anyone until the planets align and the name server records line up.
Even my web site still has a few bots and spiders and other systems munging through it. I wonder if they’ll notice when I turn it off?
One other thing I have observed. The spammers also don’t respect caching of DNS records, but in the opposite manner. Instead of caching a record for too long, they completely ignore the cache settings to make sure they can flood your new mail server with as much crap as possible, as quickly as possible.
Ah, gotta love it!
[tags]DNS, spam, caching, name server, records, nuisance, email migration, greg hughes[/tags]
One Comment
bezell
January 4th, 2007
at 11:11am
Having spent many years dealing with various mail servers for several different companies, I can identify. Here’s some of my experiences:
-No one follows DNS TTL.
-Updated MX records are usually discovered by good operations within 30m to 1h. Spammers will continue to hit the old servers due to DNS caching.
-http://www.dnsstuff.com is your friend.
-Mail is not like a website. DNS and MX records are handled differently by different mailservers. Some cache DNS, some don’t. Expect mail to continue to hit the old servers for 2 days.
-Never cold drop one mail hosting company like you might a web hosting company for the reasons listed above. The same goes for DNS.
-Ensure that PTR records match your mail server’s A record.
-Ensure your registrar has the correct nameservers listed.
-Laugh in SPEWS and anyone who uses them. They are ridiculous. I’ve been listed there before for as little as a read receipt.
-AOL will whitelist you if you can prove yourself legit. They will even forward all messages marked as spam to an administrative account for verification. Be polite and you can get escalated from their common-user 800 service number.
-Want to learn more about SPAM filtering? Check out ASSP http://assp.sourceforge.com). It’s a simple perl port 25 filter that will do nearly any check you can think of. Web-based with FANTASTIC explanations right from the interface. Works with any mail system or operating system that can use PERL. This means you, Exchange people.