Catchall domains

Catchall domains accept any mail to any email address at that domain. They were quite common, particularly at smaller domains, a long time ago. For various reasons, most of them having to do with spammers, they’re less common now.

Most folks think catchall domains are only used for spamtraps. As a consequence, many of the address verification tools will filter out, or recommend filtering out, any address that goes to a catchall domain. They test this by trying to send emails to random addresses like sldqwhhxbe+ym7ajymw23gm0@clientspecific.domain.example.
But not all catchall domains are used for spamtraps. Every client here at WttW gets a domain assigned to them and those domains are catchalls. Emails to those domains go into a database for analysis. Clients (and I!) can create any LHS on the fly to test signups, look at mail flows. Having a catchall means we don’t have to actually configure any address so I can test multiple signups and encode the data about the signup in the to: address.
This works most of the time, at least until verification services mark those addresses as bad and they don’t get imported into the client’s processes. We have some workarounds, and can still get mail despite the services making assumptions.
 
 

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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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Can you verify email addresses in real time?

In a recent discussion about spamtraps and address lists and data collection a participant commented, “[E]very site should be utilizing a real-time email address hygiene and correction service on the front end.” He went on to explain that real time hygiene prevents undeliverable addresses and spamtraps and all sorts of list problems. I was skeptical to say the least.
Yes, there are APIs that can be queried at some of the larger ISPs to identify if an account name is taken, but this doesn’t mean that there is an associated email address. Yes, senders can do a real time SMTP transaction, but ISPs are quick to block SMTP transactions that quit before DATA.
I decided to check out one service to see how accurate it was. I’m somewhat lucky in that I created a username at Yahoo Groups over a dozen years ago but never activated the associated email address. This means that the account is shown as taken and no one else can register that address at Yahoo. But the address doesn’t accept any mail.

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Trust the list broker

Over the years I’ve worked with companies who admit to me that they’ve purchased data at one point or another. Let’s face it, as bad a practice as it is, people and companies still think they can succeed in email marketing with purchased lists.
As part of the cleanup process, I start to ask questions about the list. Who did you buy it from? How were the addressees collected? Are these addresses shared with others? What did the seller tell you about the list.
Thief.
Clients are rarely able to tell me about where the addresses are collected or if they’re shared.
It’s amazing to me how many companies choose to outsource the creation of such a valuable asset. They don’t know anything about it, but it’s a huge asset and so important they won’t let go when it doesn’t work.
Some of it is the sunk cost fallacy. But I think in some cases my clients don’t really believe the person who sold them the list wasn’t truthful. They really believe there is value in the list, if they can only unlock it.
Companies selling lists don’t really have any incentive to spend time or money making sure they have permission or that the lists are good. That’s just expense to them and returns no value. The value is in the number of addresses they can sell, not in the number of responsive addresses.
How many companies buy a list and immediately take it to a list cleansing service? Why should they? Shouldn’t the company SELLING the list make sure they’re selling deliverable addresses? Shouldn’t the seller spend the money for verification?
The very fact that so many companies believe they need to clean a purchased list speaks to the horrible quality of purchased lists. And, yet, companies are addicted to the idea of purchasing lists. They trust that the addresses are collected in a permission based manner. They believe when sellers tell them the addresses are good and valid – even when they see that 10 or 20 or 30% of the list is cleaned off by the list services.
List sellers won’t do the cleaning because they know they’re not providing the product. It’s a con and it’s a swindle and yet marketers still think they’re getting something of value from list sellers. And they still discover purchased lists are horrible in terms of deliverability and performance.

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