Knowledge base
Address checker
Whether an address is worth sending to, before the first message.
Details
- The address checker says whether an email address is worth sending to: valid, risky, invalid or unknown, with the reasons. It reads the syntax, the mail servers of the domain, whether the mailbox is a throwaway or a shared one such as info@, and whether the domain looks like a typo of a well known one, with the correction it suggests.
- The check sends nothing to the address, so its owner never finds out it was checked. The free Email address checker on the tools page checks one address at a time and stores nothing.
- With an API key that can read mail, the check also says what your workspace already knows about the address: that mail to it bounced before, or that the workspace no longer sends to it.
- A deep check also asks whether the mailbox exists. It is billed per address through pay as you go, and with pay as you go off it is refused and nothing is billed.
- The checker is on the REST API as GET /tools/address for one address and POST /tools/addresses for up to 100, on the SDK as tools.checkAddress and tools.checkAddresses, on the command line, and on the MCP server as checkAddress.