qmail-smtpd is the most common method of accepting email messages for delivery from the network, but it is not the only one that comes with qmail. There is another program that comes with qmail called qmail-qmtpd. As the name indicates, just as qmail-smtpd is a Simple Mail Transfer Protocol (SMTP) server, the qmail-qmtpd program is a Quick Mail Transfer Protocol (QMTP) server.

While SMTP is the standard protocol for email transmission on the Internet, there are many email servers and clients that do not strictly adhere to the definition and requirements of SMTP. Most of them, however, deviate from the SMTP standard in predictable, common ways. This has become, in essence, a distinct de-facto protocol that was dubbed by Dr. Bernstein the Old-Fashioned Mail Injection Protocol (OFMIP).