Why should someone pay for PowerMTA ?
It is CHEAP. It is certainly not expensive when it is compared to rival softwares in the market.
It is STABLE. Leave it untouched for 1 year and you will still see it working after then.
It is FLEXIBLE. It is so flexible that you can integrate it to any ready-made or custom softwares without a hassle.
It is ECONOMIC. You will save up money by using 1 or 2 servers instead of 40-50 servers.
It is EFFICIENT. You will get the same performance results from a single server with PowerMTA installed when compared to 30-40 Postfix installed servers.
Conclusion; Pay once,profit lifetime!