What are Catch-All Emails and Why Should You Care?

When you validate the email john.smith@acme.com, you might expect a definitive answer: does this mailbox exist or not? But if acme.com is a catch-all domain, you'll never get a definitive answer from SMTP alone. Here's what catch-all means and how to handle it intelligently.

What is a Catch-All Domain?

A catch-all (or "wildcard") configuration tells the mail server to accept email sent to any address at the domain, regardless of whether a mailbox with that name actually exists. The server then either routes these messages to a single inbox or silently discards them.

Why would anyone configure this? Common reasons include wanting to ensure no customer email is ever bounced, during domain migrations, or for legacy systems where mailbox lists are not cleanly maintained.

How Common Are Catch-All Domains?

In ValidoAPI's production traffic, approximately 8-12% of business email domains have catch-all configured. This is especially common with older enterprise domains, Indian B2B companies, and businesses running their own mail servers.

How ValidoAPI Handles Catch-All

When ValidoAPI detects a catch-all domain, it returns is_catch_all: true and sets the result to risky rather than valid or invalid. This gives you the flexibility to decide how to handle these addresses based on your business context.

{
  "email": "user@catch-all-domain.com",
  "valid": true,
  "is_catch_all": true,
  "result": "risky",
  "score": 55,
  "reason": "catch_all_domain"
}

What Should You Do With Catch-All Emails?

• Marketing emails: Consider excluding or suppressing catch-all addresses until engagement is confirmed
• Transactional emails (order confirmations, etc.): Allow them — a wrong address is the customer's problem
• Free trial signups: Treat with extra scrutiny — consider requiring email confirmation before activating
• B2B lead forms: Accept and flag for manual review if the domain appears suspicious