Catch-all servers: why we label them instead of hiding them

Most mail servers will tell you when an address doesn't exist. A catch-all server won't. It says yes to everything, including addresses nobody has ever used, and sorts the mail out afterwards.

Why that matters

When we check an address, we're asking the server whether it would accept it. A catch-all always says yes. So a yes from a catch-all tells you nothing, and the address could be a real person's or a typo.

That isn't a flaw in the address. It's a setting on the server, and plenty of small businesses use it. Of the 1.5m emails we hold, 607k sit on catch-all servers.

Why we keep them

The easy move is to throw them away. But a catch-all domain is often a small firm with two people and one inbox, and the address you've got is probably fine. Dropping them would hide real contacts, and we don't hide what we hold.

So we keep the address and label it Catch-all server. You decide whether to send.

How to send to them safely

• Prefer a named mailbox. A director's own address is a better bet than a guess at the format.
• Send in small batches. Watch how many bounce before you send the rest.
• Use another route as well. A phone call or a LinkedIn message doesn't depend on the mail server.
• Keep your mailbox healthy. A run of bounces hurts your sending reputation, so stay inside your pace and check your health score.

What we do about it

We keep checking. If a second independent source agrees on an address, it can become Proven even on a catch-all. Until then, it's Claimed, and the label says so.

Read more about the email labels.