Limitation

Dear friends

I am newbee here so excuse me if my question is wrong

I wish to Impliment this easy mail server on my environment before that I wish to know is it have any limitation of users , and also 1) what specification is required if I am using it for 1000 users ,
2) advantages of spam filtering and virus scaning
3) I need a good tutorial for inatallation and configuration from A to Z

Thanks