Since email list cleaning is a big part of our business and a service Email Answers offers, as you might imagine, we see a whole bunch of email data and occasionally have some interesting surprises when validating it.
This topic sits inside a broader pre-send hygiene framework. For a practical overview of removing junk and high-risk addresses before mailing, see our guide on email list cleaning and hygiene.
This week we had a customer who sent us a list of approximately 300,000 email records. After cleaning and validating the list, it had been reduced by over 70%, which was the first sign of a problem and things to come. Since the average loss, after validating a decent optin email list, is between 3% – 10%, this usually means two things. Firstly, the list is very old and secondly, the list was probably purchased. Hence, the reason you should never waste your time or money buying an email list.
After returning the list to the customer, he found an ESP that would allow him to send an email campaign to the list and the results were dismal. Although he was only given a short leash and allowed to test 10,000 of the list, the results weren’t surprising, based on the age and type of list it was. Of the 10k emails sent, he had 54 opens, which translates to an open rate of 0.54%. The interesting thing was that the majority of the emails were delivered, but delivered to whom? This is the big question.
We then dug a little deeper into the list. We found a large percentage of emails were from @Bigfoot.com. In the early years of the Internet, (starting circa 1995), Bigfoot provided an email forwarding service, which most of us thought had vanished with the Dot-Com Bubble Burst of 2000. The interesting fact is that they still, to this day, provide this forwarding service. So the email account you had with Bigfoot in 1997 is still forwarding email to the other email account you haven’t had since 2001.
Hold on a minute, it gets better.
When Bigfoot accepts email and then forwards it on to the email it was setup to forward to, even if it doesn’t exist, Bigfoot never responds and informs the sender that the email is invalid or bounced. Sort of like a big black hole that exists at Yahoo on occasion.
When addresses behave this way at scale, they can quietly undermine sending stability over time. List quality and sender reputation are closely connected, which is explained in more detail in understanding the importance of your email sender and IP reputation.
Are you totally confused yet?
This discussion is not about predicting inbox placement or guaranteeing delivery outcomes. It focuses on why certain categories of addresses introduce risk or low value in real-world sending, and why responsible list hygiene often includes removing them before campaigns are launched.
Since part of our email validation process involves connecting to the email server, of the email address being tested, to see if it will accept email, without ever sending an email to the end user, this makes it much more difficult and virtually impossible for the “final destination email” to be validated.
This is not about predicting inbox placement or guaranteeing delivery outcomes. It’s about understanding why some addresses create risk or low value in real-world sending—and why responsible list hygiene often includes removing categories of addresses that repeatedly underperform or introduce unnecessary exposure.
If you are preparing to send a campaign, a practical hygiene step is removing known junk and high-risk address categories beforehand. PureList’s email list cleaning service focuses on removing these types of addresses so campaigns are not burdened by data that introduces unnecessary risk.
Let me attempt to confuse-simplify this for you.
If joe@email.com accepts every single email sent to it and forwards it to joe@other-email.com, but joe@other-email.com is a non-existent email address or is no longer valid, and joe@email.com never replies telling you that joe@other-email.com isn’t a valid email, how are you supposed to know? Better yet, since joe@email.com is valid and accepts email, we have to mark this email as valid, even though it is not valid, because it accepts email.
Now you know how a “Valid and Deliverable Email is Neither Valid nor Deliverable”.
This article is part of our broader resource on email list cleaning and hygiene, which explains how removing junk before sending helps reduce unnecessary risk.