Dear all ISPConfig3 Postfix users, Since I need to send out account passwords to users by emails, hacker may intercept these credentials when listening to the tcp out port 25 of my ispconfg server. Now my question is: how to force postfix to use secure smtp to send out email? That is to secure the path from my ispconfig3 server to my customer's email server. For instance, if he is a msn user, the picture becomes: My ispconfig 3 Postifx server ------ smtp ------> msn mail server Then, how do we secure the above path? Faithfully.
This is not possible. For example: How does the MSN Server know how to decrypt the secure connection? As long as you are using keys which are globally known, everyone can ready and decrypt your connections. The only solution is to use for example pgp. The downside is, that your client needs your public key to decrypt you messages, which you shouldn't send via email ;-).
I guess he meant that he just want to force tls for outgoing emails. Please take a look here ofr some instructions: http://serverfault.com/questions/120123/forcing-smtp-outgoing-mail-encryption-on-postfix
