List verification
Catch-all detection
How EmailPal detects catch-all domains by probing a mailbox that cannot exist before trusting RCPT TO on your contact. Catch-alls are their own verdict, never a valid you cannot rely on.
The probe
Many business domains accept mail to any local part. A verifier that only asks "does jane@company exist?" hears yes for jane, for asdfghjkl, and for your typo. Those later bounce — or worse, sit in a bit bucket nobody reads — after your warmed mailbox has already spent the send.
EmailPal asks about an address that cannot be a real mailbox first. If that is accepted, the domain is catch-all. Your contact is not confirmed.
No message is sent. RCPT TO only. One probe per domain is cached for a day so a large CSV does not hammer the same MX for every row.
What is a catch-all email? is the definition. This page is the mechanism. The six-way result set: Six verification verdicts.
Why other tools call catch-alls valid
SMTP's RCPT TO was not designed as a people-directory. On a well-behaved server, a yes means the mailbox exists and a no means it does not. On a catch-all, both answers are yes. A two-state verifier has nowhere to put that and picks valid because valid is the happy path.
EmailPal's six verdicts exist so we do not have to lie. Catch-all is a first-class answer. Unknown is a first-class answer when the server greylists the probe.
This is the same engine on the dashboard, POST /api/public/v1/verify, and the verify_list MCP tool. List verification by EmailPal.
What we do not do
- We do not deliver a message. There is no "confirmation email" to the prospect.
- We do not try 50 random local-parts per domain. One impossible mailbox is enough to learn the policy; we cache it.
- We do not upgrade catch-all to valid because a third-party enrichment API said the person works there. That is a different data source. Use it if you want; do not ask us to relabel SMTP.
FAQs
Should I ever mail catch-alls?
That is your risk budget. We will not pretend they are valid. Many teams drop them; some mail a LinkedIn-matched subset at lower volume. On a brand-new or newly claimed mailbox, drop them.
Can a domain be catch-all for some MX and not others?
We report what the server we reached told us. If results look mixed, the domain may be greylisting probes — verdict unknown is the honest answer.
Why did a real person come back catch-all?
Because we cannot distinguish them from a typo. The domain accepted a mailbox that cannot exist. The person can still be real. SMTP cannot say so.
Does this slow down a 10,000-row upload?
The expensive part is talking to MX hosts. Caching the per-domain probe is how a list of 200 people at the same company does not become 200 catch-all probes.