That fixes half of the story; the other half is inbound spam filtering (with all the RBL, greylist, spamassassin dance). I then prefer an unique solution such a

That fixes half of the story; the other half is inbound spam filtering (with all the RBL, greylist, spamassassin dance). I then prefer an unique solution such as http://mailroute.net http://mailroute.net that handles both inbound and outbound. PS: mailgun is really great, i'm a happy user