I'm creating newsletter in asp.net. I'm sending to 2000 email recipients. This operation iterate every mail and send using SMTP mail. Please see my previous question .My server use hmailserver.
My problem is
Sometimes this error shown: Mailbox unavailable. The server response was: 5.1.1 Recipient address rejected: User unknown in relay recipient table
or
Mailbox unavailable. The server response was: Unknown user Mailbox unavailable. The server response was: Unknown user