I think that we can make Apple Mail Services do what we need.
/etc/postfix/main.cf is a key file
These instructions are key as well
http://article.gmane.org/gmane.comp.cms.sakai.devel/6139/
Autostart is done using launchctl – do
man launchctl
man launchctl.plist

Notes – some sakai.properties values:
# EMAIL CONFIGURATION
# smtp server for outgoing emails
smtp@org.sakaiproject.email.api.EmailService=mail.yale.edu
# dns addresses used by James for incoming email
smtp.dns.1=130.132.1.9
smtp.dns.2=130.132.1.10
smtp at org.sakaiproject.service.framework.email.EmailService=mail.unisa.ac.za
smtp.dns.1 = 163.200.97.20
smtp.dns.2 = 163.200.97.131
smtp.port = 25
smtp.enabled = true
serverName = vula.uct.ac.za
serverUrl = https://vula.uct.ac.za
# dns addresses used by James for incoming email
smtp.dns.1 = 137.158.128.11
smtp.dns.2 = 137.158.128.4
# SMTP port on which James runs. Default is 25. Recommend running on 8025,
# and using a standard mailer on 25 to forward mail to Sakai.
smtp.port = 8025
# flag to enable or disable James for incoming email (true | false)
smtp.enabled = true
# smtp server for outgoing emails
smtp@org.sakaiproject.service.framework.email.EmailService=localhost