Email verification services


Just yesterday a group of delivery folks were discussing email verification services over IRC. We were talking about the pros and cons, when we’d suggest using them, when we wouldn’t, which ones we’ve worked with and what our experiences have been. I’ve been contemplating writing up some of my thoughts about verification services but it’s a post I wanted to spend some time on to really address the good parts and the bad parts of verification services.
Today, Spamhaus beat me to the punch and posted a long article on how they view email verification services. (I know that some Spamhaus folks are part of that IRC channel, but I don’t think anyone was around for the discussion we had yesterday.)
It’s well worth a read for anyone who wants some insight into how email verification is viewed by Spamhaus. Their viewpoints are pretty consistent with what I’ve heard from various ISP representatives as well.
In terms of my own thoughts on verification services, I think it’s important to remember that the bulk of the verification services only verify that an address is deliverable. The services do not verify that the address belongs to the person who input it into a form. The services do not verify that an address matches a purchased profile. The services do not verify that the recipient wants email from the senders.
Some of the services claim they remove spamtraps, but their knowledge of spamtraps is limited. Yes, stick around this industry long enough and you’ll identify different spamtraps, and even spamtrap domains. I could probably rattle off a few dozen traps if pressed, but that’s not going to be enough to protect any sender from significant problems.
Some services can be used for real time verification, and that is a place where I think verification can be useful. But I also know there are a number of creative ways to do verification that also check things like permission and data validity.
From an ESP perspective, verification services remove bounces. This means that ESPs have less data to apply to compliance decisions. Bounce rate, particularly for new lists, tells the ESP a lot about the health of the mailing list. Without that, they are mostly relying on complaint data to determine if a customer is following the AUP.
Spamhaus talks about what practices verification services should adopt in order to be above board. They mention actions like clearly identifying their IPs and domains, not switching IPs to avoid blocks and not using dozens or hundreds of IPs. I fully support these recommendations.
Email verification services do provide some benefit to some senders. I can’t help feeling, though, that their main benefit is simply lowering bounce rates and not actually improving the quality of their customers’ signup processes.

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  • Verification at the point of collection makes some sense. But verification of existing lists is what’s dismissively called list washing. If your list is dirty enough to need washing, washing won’t help.

  • While it is called listwashing, I think there’s several use cases for validation after collection, the most obvious of which is: you’re an ESP and a customer brings you a list. How do you tell how bad it is without mailing it? Or M&A: you buy a smaller company and get their list. Will mailing it hurt you? Or politics: you ran for state senate last year, and this year you’re running for US Senate. How much of your list is still good?
    And like Laura says, there are eyeball tests. If I notice John Levine’s address on the list of a dance club on the Isle of Man, I can email John and ask him how many european dance clubs he goes to these days. If I see a bunch of addresses at domains that I know haven’t been legitimate for several years, that tells me something.
    But in a vacuum, how can I know that some plausible-looking name @ is a good address and they actually want this mail? That’s tricky. And having more tools to help figure that out — that are not themselves abusive — can’t hurt.

  • @John L – couldn’t agree more!
    While I think these types of vendors have value, there is no replacement for proper opt-in, acquisition, and COI at the top of the funnel to provide the best opportunity for a clean list. Using secondary list verification services after the fact is a “feel good” approach for senders to say “yep, we have a clean lists!”
    Devil is in the details – bounces, complaints, BL listings, and low engagement don’t lie.

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