I've been stumbling upon this for a few days now. I use OSX Mail and somehow I just can't configure it to work with my Debian Squeeze with ISPConfig 3. Problem: ISP blocks port 25 So I try to connect through 465 And yes I want a secure connection... What I've done: Decomment in /etc/postfix/master.cf Code: smtps inet n - - - - smtpd Restart postfix Enable firewall port 465 Checked telnet, outcome on port 465: Code: Escape character is '^]'. 220 vps.domain.com ESMTP Postfix (Debian/GNU) ehlo localhost 250-vps.domain.com 250-PIPELINING 250-SIZE 250-VRFY 250-ETRN 250-STARTTLS 250-AUTH PLAIN LOGIN 250-AUTH=PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN Seems okay right? But OSX mail keeps complaining it cannot reach the server. Mail retrieval is possible. In both cases I use mail.domain.com (IMAP and SMTP. So different operating system then... Ubuntu 10.10 mail client (Evolution). It works but only if I use TLS. Back to OSX.. nope.. doesn't work. I've already specified to use port 465 on Advanced settings. But just can't figure it out. I've even done a full reboot of the server... enabled/disables ssh, but no luck so far. Pleeezz help , how do I configure my server OSX Mail also works.