E-MailRelay is a simple SMTP proxy and store-and-forward message transfer agent
(MTA). When running as a proxy all e-mail messages can be passed through a
user-defined program, such as a spam filter, which can drop, re-address or edit
messages as they pass through. When running as a store-and-forward MTA incoming
messages are stored in a local spool directory, and then forwarded to the next
SMTP server on request.
