On 6/27/12, Götz Reinicke <goetz.reinicke at filmakademie.de> wrote: > Long story short: I advised the use of port 587 two hours ago. > > FYI since than I had 169 outgoing connections to port 20 and 1 to 587. :) Seriously, just force them. I got so tired of one particular app/mail server that keep getting blacklisted because of lazy client admin and users, I sent them a notice that for emergency security reasons, emails will only be accepted on port 587. Gave them one hour, then closed 25. Understandably people screamed for about another hour or so but all of them ended up on 587 by the end of the day ;)