MailVeri

That address list from a few years ago still looks fine in the spreadsheet. Send a newsletter or sales email to it, and part of the mail comes back because those mailboxes no longer exist. Email providers count many returned mails against the sender, so later mail is more likely to go to spam. MailVeri checks each address before you send and tells you whether the mailbox still exists.

The check runs in three steps: whether the address is written correctly, whether the domain can receive mail, and whether the receiving server has that mailbox. For the last step, MailVeri starts a mail delivery and stops before anything is sent. The report gives each address a status. Besides valid and invalid, it marks disposable addresses, role addresses such as info@ or support@, catch-all domains that accept any address, and full inboxes. Addresses the check cannot settle are marked as unknown.

MailVeri also publishes an MCP server on GitHub under the MIT licence. With it, an AI assistant, for example Claude or Cursor, can check an address or start a bulk check from a chat. Ready-made templates connect the service to automation tools like n8n and Zapier.

Lists of up to one million addresses can be uploaded to the web app as spreadsheets or text files. For signup forms, a REST API checks one address at a time, and the site says each check takes under a second.