gtk-send-pr is a problem report tool, designed to send reports to a GNATS database server using libesmtp to deliver mail. The program has a user friendly interface and lets you use any SMTP server, including support for AUTH and TLS.
ESMTP MTA is a user configurable relay-only MTA with a sendmail-compatible syntax, based on libESMTP and supporting the AUTH (including the CRAM-MD5 and NTLM SASL mechanisms) and the StartTLS SMTP extensions.