I know this is basically a spam tool.

I think to know that you can query some info from a mailserver to test if an address exists.

I would like to find hidden addresses of some companies, for example I want to test if info@companyname.com exists.

Anyone know how to do that?

Update

I learned quite a bit

• Mailserver block the requests that are used to get a list of inboxes (“accounts”)
• many servers will block mailservers that are not on an allowlist
• many servers will block servers, if mails were sent to nonexistent addresses a couple of times
• the message “recipient not known” will not appear often, as servers may “black hole” a senders mail and cut off the connection without sending the status message back