Description:

Exim is a mail transport agent (MTA) developed at the University of
Cambridge for use on Unix systems connected to the Internet. In style
it is similar to Smail 3, but its facilities are more extensive, and
in particular it has options for verifying incoming sender and
recipient addresses, for refusing mail from specified hosts, networks,
or senders, and for controlling mail relaying. Exim is in production
use at quite a few sites, some of which move hundreds of thousands of
messages per day.

You can build exim with some conditional build swithes;

(ie. use with rpm --rebuild):
--with[out] mysql MySQL lookup support (enabled)
--with[out] pgsql PostgreSQL lookup support (disabled)
--with[out] monitor The Exim Monitor (enabled)
--with[out] exiscan SpamAssassin support (enabled)
--with[out] srs_alt Experimental SRS support (disabled)
--with[out] spf2 Experimental SPF2 support (disabled)
--with[out] sqlite3 SQLite3 lookup support (enabled)
--with[out] ldap LDAP lookup support (enabled)
--with[out] sals2 SASL2 auth support (disabled)
--with[out] logrotate Logrotate (enabled)