TLDR:

Every email is validated. We use a combination of two verifiers and a custom provider score to classify the email into three categories:

These emails bounce around 1% of the time.

If the email is invalid, we continue enrichment until we find a valid email. Invalid emails found do not consume credits.

Traditional methods cannot confidently determine if these emails are valid or not. In this case, we use a 3rd validation method to gain more insight into the deliverability of this email:

Here's what this process looks like in a diagram:

We benchmarked different email verification services.

https://fullenrich.com/email-verifier-comparison

We found that even when a verification service flags an email as "valid," it still bounces way too often—around a 10% bounce rate.

This is because those "valid" emails are actually catch-all. It received a positive response but failed to flag it correctly as catch-all. By using multiple verification services simultaneously, we can determine with high confidence if a domain is catch-all rather than simply valid.

Email verification is a method used to confirm that an email address is capable of receiving messages. Understanding this process can help make sense of the "Deliverability Status" given to each email by FullEnrich. Let's use the email "[email protected]" as an example to explain the steps involved:

Syntax Check: First off, the system checks if the email address is formatted correctly. For example, 'greg@fullenrich' won't pass the test, but '[email protected]' will.

Domain Verification: Next, the system verifies that the domain (in this case, fullenrich.com) is a real, active domain.

Mail Exchange (MX) Record Check: This step is about confirming the domain's MX records. It's crucial to ensure there’s a mail server ready to receive emails. Basically, the system checks if there’s an email server that can handle emails sent to "@fullenrich.com".

Ping Test: This step involves sending a simple message or 'ping' to the email address. This is done to check if the specific email (like [email protected]) is active and can receive emails. It’s important to note that this doesn't involve sending an actual email to the address.

Catch-all Test: If the ping test is positive, we might still have a problem. Some email servers are configured to always send “Yes” to the ping test even if the email does not exist. This is known as a catch-all configuration. To trust the ping test, we need to ensure the email server is not in a catch-all configuration. Therefore, the verification service will send multiple other pings to random emails to ensure they don’t reply “Yes” to those fake emails.

Each of these steps helps ensure the email address is not only valid but also active and able to receive messages.

Catch-all email verification uses two main methods.

The system tests hundreds of sites like Notion, Spotify, and Google Drive. It tries to log in using the email and a fake password. If the site says "wrong password," an account exists. If it says "no user with this email," the email isn't used there.

This method isn't perfect. An email might have been used before but isn't active now. So we can't always be 100% sure. The system only knows if an account exists, not if the email is still valid.

Sometimes, our email verification systems detect a problem at the domain level rather than with the specific email address. This could be due to an anti-spam system, specific email delivery settings, or other issues.

From our experience, any email found under these conditions tends to bounce at a much higher rate than others (70 to 95% bounce rate). Therefore, we stop the workflow immediately because we know we won’t be able to provide an email we are confident in.

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