You can do several tests of messages entering the qmail system:1. SMTP server test: Forge some mail locally via SMTP. Replace ``me''   with your username and ``domain'' with your host's name.       % telnet 127.0.0.1 25       Trying 127.0.0.1...       Connected to 127.0.0.1.       Escape character is '^]'.       220 domain ESMTP       helo dude       250 domain       mail <me@domain>       250 ok       rcpt <me@domain>       250 ok       data       354 go ahead       Subject: testing              This is a test.       .       250 ok 812345679 qp 12345       quit       221 domain       Connection closed by foreign host.       %   Look for the message in your mailbox. (Note for programmers: Most   SMTP servers need more text after MAIL and RCPT. See RFC 821.)2. Remote-local test: Send yourself some mail from another machine.   Look for the message in your mailbox.3. Remote-error test: Send some mail from another machine to   nonexistent@domain. Look for a bounce message in the remote mailbox.4. UA test: Try sending mail, first to a local account, then to a   remote account, with your normal user agent.5. Remote-postmaster test: Send mail from another machine to   PoStMaStEr@domain. Look for the message in the alias mailbox,   normally ~alias/Mailbox.