There are a number of transports compiled into smail that utilize the UUCP suite. In a UUCP environment, messages are usually passed on by invoking rmail on the next host, giving it the message on standard input and the envelope address on the command line. On your host, rmail should be a link to the smail command.
When handing a message to the UUCP transport, smail converts the target address to a UUCP bang path. For example, user@host will be transformed to host!user. Any occurrence of the `%' address operator is preserved, so user%host@gateway will become gateway!user%host. However, smail will never generate such addresses itself.
Alternatively, smail can send and receive BSMTP batches via UUCP. With BSMTP, one or more messages are wrapped up in a single batch that contains the commands the local mailer would issue if a real SMTP connection had be established. BSMTP is frequently used in store-and-forward (e.g. UUCP-based) networks to save disk space. The sample transports file in appendix- contains a transport dubbed bsmtp that generates partial BSMTP batches in a queue directory. They must be combined into the final batches later, using a shell script that adds the appropriate HELO and QUIT command.
To enable the bsmtp transport for specific UUCP links you have to use so-called method files (please refer to the smail(5) manual page for details). If you have only one UUCP link, and use the smart host router, you enable sending SMTP batches by setting the smart_transport configuration variable to bsmtp instead of uux.
To receive SMTP batches over UUCP, you must make sure that you have the Un-batching command the remote site sends its batches to. If the remote site uses smail, too, you need to make rsmtp a link to smail. If the remote site runs sendmail, you should additionally install a shell script named /usr/bin/bsmtp that does a simple ``exec rsmtp'' (a symbolic link won't work).