[OT] What is a condition for ideal mail server?

[Byung-Hee HWANG]

Hi, i'm not a serious hacker nor a power user for Postfix. I'm just 
using Postfix. Recently, i'm interested in setup ideal mail server for 
outgoing. Already i moved my mailbox to Google Apps because i could not 
handle so many spam. So now making receiving SMTP is not my concern. 
Only my concern is to make outgoing SMTP in perfect.

As fas as i know, here are many Postfix guru. So just i wish to hear 
various opinions about making outgoing SMTP perfectly. Whenever i have 
some times, i search about DKIM and RFCs for SMTP standard. What is the 
real point for ideal outgoing mail server? I investigate with some mail 
servers on the Internet, postfix.org's MX, isc.org's MX and 
freebsd.org's MX and gnu.org's MX, ietf.org's MX, mipassoc.org's MX, 
gmail.com's MX, some univeristy's MXs, etc.

After all, i thought that the conditions for perfect outgoing mail 
server are providing a correct rDNS and a correct signature as like DKIM 
and a correct certificate-based authentication as like TLS. Besides 
that, is there any the conditions? Well, i just curious about that..

Sincerely,

byunghee