open smtp performance

[Krzysztof Dabrowski]

i have a little question regarding open smtp's performance under heavy load.
Running a separate shell process and then recreate tcprules for every pop3
connection looks like an overkill for me. We have a 3000+ users serer here
and we HAVE to implement some kind of authentication before relaying and we
can not just allow certain IP's as few of our customers are using IPass or
public dialups here.
If opensmtp is not suitable for us then could you poing me to any alternative?

Krzysztof Dabrowski