OpenSMTPd will be the default Mail Transfer Agent in OpenBSD 5.6

[jggimi]

From the OpenBSD Journal:

After a long time spent in the shadow of Sendmail, OpenSMTPd is now the default MTA in OpenBSD...

From the Following -current FAQ, for those running -current:

2014/03/12 - smtpd becomes default MTA

The default system MTA is now smtpd. If you are running sendmail with
anything other than the default configuration, please exercise caution
and care when upgrading. The sendmail cronjob should be disabled, 
/etc/mailer.conf and /etc/rc.conf{,local} should be checked to verify 
one and only one MTA is enabled, and newaliases run.

    crontab -e
    vi /etc/mailer.conf
    vi /etc/rc.conf
    vi /etc/rc.conf.local
    newaliases