In the UK edition of The Register there is an article about a guide
recently published by European Commission "The IDA Open Source Migration
Guidelines"
http://www.theregister.co.uk/content/4/33560.html
In that guide which you can find here (URL wrapped)...
http://europa.eu.int/ISPO/ida/jsps/index.jsp?
fuseAction=showDocument&parent=news&documentID=1647
PDF of the 148 page document here...
http://europa.eu.int/ISPO/ida/export/files/en/1603.pdf
** Exim ** is listed as the open source MTA of choice over sendmail,
postfix and Courier-MTA.
Qmail is bounced out as it is described as not really being open source
because of "Its restrictive license...", qmail users must also get tired of
looking at the number 1.03 :-)
PS