Related Posts

Analysing lead-gen spam

Yesterday I showed how major companies hire hard core spammers.
Today I’m going to show you some of the technical details as to how I found that data. This is a fairly quick and shallow analysis, the sort of thing I’d typically do for a client to help them decide whether the case was worth pursuing before expending too much money and time on investigation and legal paperwork. I’ve also done it using standard command line tools that are available on pretty much any unix command line (and windows, with a little effort).
There are several questions to answer about the email in question.

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Poor delivery can't be fixed with technical perfection

There are a number of different things delivery experts can do help senders improve their own delivery. Yes, I said it: senders are responsible for their delivery. ESPs, delivery consultants and deliverability experts can’t fix delivery for senders, they can only advise.
In my own work with clients, I usually start with making sure all the technical issues are correct. As almost all spam filtering is score based, and the minor scores given to things like broken authentication and header issues and formatting issues can make the difference between an email that lands in the inbox and one that doesn’t get delivered.
I don’t think I’m alone in this approach, as many of my clients come to me for help with their technical settings. In some cases, though, fixing the technical problems doesn’t fix the delivery issues. No matter how much my clients tweak their settings and attempt to avoid spamfilters by avoiding FREE!! in the subject line, or changing the background, they still can’t get mail in the inbox.
Why not? Because they’re sending mail that the recipients don’t really want, for whatever reason. There are so many ways a sender can collect an email address without actually collecting consent to send mail to that recipient. Many of the “list building” strategies mentioned by a number of experts involve getting a fig leaf of permission from recipients without actually having the recipient agree to receive mail.
Is there really any difference in permission between purchasing a list of “qualified leads” and automatically adding anyone who makes a purchase at a website to marketing lists? From the recipient’s perspective they’re still getting mail they don’t want, and all the technical perfection in the world can’t overcome the negative reputation associated with spamming.
The secret to inbox delivery: don’t send mail that looks like spam. That includes not sending mail to people who have not expressly consented to receive mail.

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How to disable a domain

Sometimes you might want to make it clear that a domain isn’t valid for email.
Perhaps it’s a domain or subdomain that’s just used for infrastructure, perhaps it’s a brand-specific domain you’re only using for a website. Or perhaps you’re a target for phishing and you’ve acquired some lookalike domains, either pre-emptively or after enforcement action against a phisher, and you want to make clear that the domain isn’t legitimate for email.
There are several things to check before disabling email.
1. Are you receiving email at the domain? Is anyone else?
Check the MX records for the domain, using “host -t mx example.com” from a unix commandline, or using an online DNS tool such as xnnd.com.
If they’re pointing at a mailserver you control, check to see where that mail goes. Has anything been sent there recently?
If they’re pointing at a mailserver that isn’t yours, try and find out why.
If there are no MX records, but there is an A record for the domain then mail will be delivered there instead. Check whether that machine receives email for the domain and, if so, what it does with it.
Try sending mail to postmaster@ the domain, for instance postmaster@example.com. If you don’t get a bounce within a few minutes then that mail may be being delivered somewhere.
2. Are you sending email from the domain? Is anyone else?
You’re more likely to know whether you’re sending mail using the domain, but there’s a special case that many people forget. If there’s a server that has as it’s hostname the domain you’re trying to shut down then any system software running no that server – monitoring software, security alerts, output from cron and so on – is probably using that hostname to send mail. If so, fix that before you go any further.
3. Will you need mail sent to that domain for retrieving passwords?
If there are any services that might have been set up using an email address at the domain then you might need a working email address there to retrieve lost passwords. Having to set email back up for the domain in the future to recover a password is time consuming and annoying.
The domain registration for the domain itself is a common case, but if there’s any dns or web hosting being used for the domain, check the contact information being used there.
4. How will people contact you about the domain?
Even if you’re not using the domain for email it’s quite possible that someone may need to contact you about the domain, and odds are good they’ll want to use email. Make sure that the domain registration includes valid contact information that identifies you as the owner and allows people to contact you easily.
If you’re hosting web content using the domain, make sure there’s some way to contact you listed there. If you’re not, consider putting a minimal webpage there explaining the ownership, with a link to your main corporate website.
5. Disabling email
The easiest way to disable email for a domain is to add three DNS records for the domain. In bind format, they look like:

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