When should I worry about performance tuning?

[Dave Horsfall]

On Wed, 29 Mar 2017, Martin MATO wrote:

> In the first case, you'll should prefer setting greylisting / tarpitting 
> at minimum, feeding a firewall table for blacklisting is a neverending 
> story (plus, there is some real chance blocking real MX relays).

A judicious selection of DNSBLs and enforcement of RFC-compliance etc do 
the trick for me; I block several hundred attempts each day, with very few 
false positives and hardly any getting through (and I don't mind wasting 
SMTP cycles).

And was the OP really blocking only a few ports and allowing the rest?  
If so, that's backwards to good practice.

-- 
Dave Horsfall DTM (VK2KFU)  "Those who don't understand security will suffer."