TL;DR
- A catch-all domain says "yes" to every address, so its addresses can't be confirmed either way.
- They bounce far more than verified addresses. In Hunter's test: 27% vs 1%.
- Don't mix them into your main campaign. Skip them on new domains, or send them separately and slowly from established inboxes.
What a catch-all domain is
When we check an address, we ask the domain's mail server whether that mailbox exists (how verification works). Most servers answer honestly. A catch-all server answers "yes" to everything, including addresses that can't exist, and decides later whether to deliver or bounce. We detect this by asking about a random address too. If that's accepted, the domain is catch-all.
Many companies use catch-all on purpose (so misspelled emails still reach someone), and some security gateways behave this way. That's why B2B lead lists contain so many of them.
How each tool treats them by default
- Instantly marks them Risky and doesn't contact them by default.
- Smartlead sends to "valid and catch-all" leads by default.
- MailExchange labels them risky: catch-all, separate from role and disposable addresses, so you decide.
A safe way to send to catch-alls
- Never on new domains. Let a domain build a few weeks of clean history first.
- Separate campaign. Keep catch-alls out of your main campaign so they can't drag its bounce rate up.
- Lower volume, established inboxes. Send them slowly from your most reputable senders.
- Watch the first few hundred sends. If bounces pass about 3-5%, stop that segment.
- Prioritise. Only send to catch-alls where the lead is valuable enough to justify the risk.