What Are Catch-All Domains?
Catch-all domains are email domains that always return a "Valid" response from the SMTP service, whether the address is valid or invalid.
There are three primary behaviors of catch-all domains.
- Emailing a nonexistent email address funnels your message into a catch-all inbox (this does not hurt your email reputation)
- Emailing a nonexistent email address results in a bounce and states the user doesn't exist (this hurts your email reputation)
- The catch-all address is valid, and your email is delivered
How does ZeroBounce handle catch‑all emails if I use Verify+?
When Verify+ is enabled, ZeroBounce automatically runs Catch‑all Email Validation on catch‑all results that haven't previously been processed by Verify+. This additional step (shown in your results as Phase 2: Catch-all Email Validation) may reclassify part of those addresses as Valid or Invalid; the remainder will stay Catch‑all. Processing can take up to 48 hours.
→ See: Email List Validation › Verify+ for details.
Do I need to re‑upload my list or run a separate job?
No. If Verify+ is enabled, Catch-all Email Validationⓘ starts automatically after Phase 1 is complete. You'll see progress and final results in the same list‑results view, and your downloads will reflect the latest classifications once Phase 2 completes.
Why do businesses use catch-all domains and addresses?
Some companies set up catch-all email addresses to "catch all" incoming emails sent to invalid addresses.
For example, if you were to email “misspelledname@domain.com”, the mail administrator would forward your message to the catch-all address. By doing this, they can review all mail sent to their email server to ensure that they don't miss important mail.
Some mail server operators also do this because they believe it will prevent individuals from harvesting real email addresses from their SMTP server.
Why are catch-all domains problematic?
The first issue with catch-all domains is that they always return a "valid" result. This means there is no way to verify whether the address is valid or invalid. Emailing a catch-all address means you risk bouncing the email.
Second, catch-all domains often receive high volumes of spam. Because mail services cannot tell if the address is quality, spam operators will send emails to them regardless.
Keeping catch-all domains on your email list risks increasing your bounce rate or reaching an inactive inbox. Repeated bounces and lower engagement will hurt your email deliverability.
How does the ZeroBounce email verifier deal with catch-all domains?
ZeroBounce identifies all email address types, including catch-all domains, with 99.6% accuracy.
Because validating catch-all domains is impossible, ZeroBounce identifies and labels these domains accordingly. From there, it's up to you to decide if you want to risk emailing these domains. While some may result in a bounce, others may be valid and allow you to connect with legitimate prospects.
If you decide to email your catch-all domains, it's recommended to segment them into a separate mailing list. Doing this lets you separate your valid, clean emails and avoid negative impacts on your marketing campaigns.
If emailing your catch-all domains results in a bounce or zero engagement, delete them from your lists.
Check out the complete guide to catch-all email domains ->
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