opinion blocking several ip ranges

[dave9000]

I have been noticing a lot of spam and portscans are coming from the class A ip ranges of 80,194,200,210,211,212

We are considering blocking these ip ranges at the router.

Anyone ever tried this and if so did it block out any of your customers ?

 

[dave9000]

well we tried it and blocked out several customers so we backed off and just blocked port 25 on those ips and our server load went down by %30