Mail Daemon

Exchange and mailer daemon

is there any one who can recommend me best out of these two ? I am using exchange and majority of my contacts out side network are comaplaining that their email are bounced back

How do i migrate from microsoft exchange to mail deamon

I have quite been using microsoft exchange for quite some time now. I lately discovered that my user licence for the users has been exhausted.Hence i my organisation continue to grow everyday with the number of users been on an increase as well. Someone gave me an idea of migrating some of my users...