Unverifiable results explained

Unverifiable results explained

Why some emails can't be checked?

Ever found yourself scratching your head because an email couldn't be verified? It's a common issue with a few usual suspects behind it. Let's dive into some of the main reasons your email verification might come back with that puzzling "unverifiable" status.

Mail server configuration

Imagine you're sending a letter, but before it reaches the mailbox, someone asks you to prove you're not just another salesperson. That's what happens in the digital world too. Many organizations protect their inboxes with layers of security to block unwanted emails, much like a digital bouncer at the door of a club. These measures include asking for verification that you're human or ensuring that only emails from known sources get through.

When we try to verify an email address, we're essentially knocking on the door of the recipient's email server. If the server is guarded by these security measures and we can't get a clear response, we're left in the dark about the email's legitimacy. In such cases, our only option is to report back that the email address is "unverifiable," not because it doesn't exist, but because we couldn't get a straight answer.

Email Verification

Catch All servers (ServerIsCatchAll)

Some email systems operate like a giant net, catching everything sent their way. These "catch-all" servers accept all emails, regardless of the specifics. While this might seem like a hospitable approach, it's akin to a mailbox that never says "no" — everything from important messages to junk mail gets a nod.

For us, trying to verify an email against such a system is like trying to find a needle in a haystack without knowing if the needle is even there. We might be told everything is fine, but that doesn't help us confirm the individual existence and validity of an email address within that domain. When we encounter a catch-all server, we're compelled to mark the verification attempt as "unverifiable," since the server's indiscriminate acceptance policy gives us no real insight.


Greylisting is an email server's way of playing hard to get. When we make our first attempt to verify an email, the server might tell us to "try again later." It's a bit like being told to wait in line. This tactic is used to deter spammers, who are less likely to retry. The server takes note of our request and watches. If we come back at the right time, it might then consider us legitimate and allow the verification to proceed.

However, this process introduces a delay and an element of uncertainty in email verification. Because greylisting varies greatly between servers and can change without notice, it often leads us to label an email as "unverifiable" during the initial attempts. It's not a definitive "no," but more of a "not right now."

Transient Network Fault

The internet is a complex network, and sometimes, things just don't go smoothly. These transient network faults are like the little glitches we all experience with our gadgets — frustrating and often inexplicable. They can occur anywhere along the path between our verification attempt and the recipient's email server.

When we encounter such a hiccup, it's as if the email server didn't hear our knock. This doesn't mean there's something wrong with the email address itself; it's just bad timing. In these cases, we mark the verification as "unverifiable," but it's worth trying again later. Much like rebooting your computer can suddenly fix issues, a second attempt at verification might go through without a hitch once the network is stable.

"Unverifiable" doesn't necessarily mean invalid; it often means we faced a hurdle we couldn't overcome at that moment. Whether it's beefy security measures, catch-all servers, strategic delays, or simple technical glitches, there are plenty of reasons why an email might not be verifiable on the first try. But with patience and perhaps a second attempt, you might find the verification you're looking for.