A catch-all domain is one where the mail server accepts every address at that domain, whether or not a mailbox exists behind it. That is a configuration choice by the receiving company, and it means no verification method anywhere can confirm the individual mailbox. Any vendor claiming otherwise is guessing.
Argorant labels catch-alls honestly rather than hiding them among valid addresses, and you decide whether to include them.
When to include them. Catch-all domains are common at larger and more traditional companies, so excluding them entirely can remove a meaningful part of some segments. If your target market is enterprise or a region where this configuration is widespread, excluding all catch-alls costs you real reach.
When to leave them out. If you are warming a new domain, if your sending reputation is already fragile, or if your provider is strict about bounce rates, keep them out until you have headroom.
The strategy most teams settle on:
- Run your main sequences on validated addresses only, from a healthy sending domain.
- Put catch-alls in a separate campaign, on a separate sending domain if you have one.
- Send that campaign at lower volume and watch the bounce rate for the first few hundred sends.
- Scale it if the bounce rate holds, pause it if it does not.
Separating them means a bad catch-all batch can never damage the reputation carrying your main campaigns.