smtp-benchmark consists of two programs, smtpsend and smtpsink.
Whereas smtpsend is used to send generated e-mail messages using SMTP
to a mail transfer agent, smtpsink is designed to dispose of received
messages as quick as possible.

smtpsend measures the time spent sending e-mails and the number
of e-mails actually sent and outputs statistics after the program
run.

smtpsend can fork one or more parallel senders each using one or more
sequential connections to a SMTP server to deliver one or more
messages per connection.

smtpsink comes in handy when the relaying performance of a MTA is
to be measured.
