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A catch-all, or accept-all, domain is configured to accept emails sent to addresses at that domain even when the individual mailbox may not exist.
This makes catch-all emailsⓘ more difficult to validate. A mail server may accept both real and nonexistent addresses, so server acceptance alone doesn’t always confirm whether an individual mailbox is valid.
Businesses may use catch-all configurations to avoid missing important messages sent to incorrect or outdated email addresses.
For example, if someone mistypes an employee’s email address or sends a message to a mailbox that no longer exists, a catch-all configuration may allow the mail server to accept the message instead of immediately rejecting it.
Catch-all configurations can also make it more difficult for outside senders to determine which individual mailboxes exist at a domain.
With a typical email address, the receiving mail server may provide enough information to determine whether the individual mailbox can accept email.
Catch-all servers behave differently. Because they may accept messages for any address at the domain, including nonexistent mailboxes, traditional validation methods can have difficulty determining whether a specific address is Valid or Invalid.
That doesn’t mean every catch-all email is invalid or unsafe. Some belong to real, active mailboxes and may represent valuable contacts. The challenge is getting enough information to distinguish those addresses from ones that don’t exist.
ZeroBounce can validate many catch-all email addresses during standard email validationⓘ and return a Valid or Invalid result without requiring an additional validation phase.
This capability works across widely used email platforms, including Google Workspace, Microsoft 365, and major Secure Email Gateway (SEG) providers.
ZeroBounce also preserves the domain-level Catch-all indicator. This means an individual address can receive a Valid or Invalid result while your validation data still shows that the domain itself is configured as catch-all.
Addresses that can’t be resolved during standard validation remain classified as Catch-all.
When Verify+ is enabled, ZeroBounce can take eligible unresolved catch-all addresses through an additional validation phase called Catch-all Email Validationⓘ.
During this phase, Verify+ performs additional checks to determine whether more individual addresses can be classified as Valid or Invalid. Addresses that still can’t be resolved remain Catch-all.
→ See: Email List Validation › Verify+ for details.
No. When Verify+ is enabled and your list is eligible for Catch-all Email Validationⓘ, the additional validation phase begins after standard validation.
You can follow the progress in the same list-results view. Once the additional validation is complete, your results and downloadable files will reflect the latest classifications.
Don’t automatically assume that every unresolved catch-all email is invalid. At the same time, sending to an address that remains unconfirmed carries more risk than sending to an address ZeroBounce has validated as Valid.
Consider segmenting unresolved Catch-all results separately from your Valid contacts and use additional information before deciding whether to email them. ZeroBounce Email Scoring and your own engagement data can provide additional signals when evaluating these contacts.
Remember that Email Scoringⓘ does not determine whether an individual mailbox is Valid or Invalid. It should be used as an additional source of information rather than as a substitute for email validationⓘ or Verify+.
Check out the complete guide to catch-all email domains ->
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