Sir,
I would like to know how to block certain sites in my office area.So that no one can use certain sites.I have a setup of 24 computers and I want to block all mail services, except companies mail. Waiting for your reply.
Thank You,
Regards,
Kiran .

Do you have a firewall setup?

I would recommend that you check out Kerio Technologies. Don't you think that it is bad management by denying your staff not to read personal mail? Depriving them to read personal e-mail can only be enforced if your employees are not getting their job done... Don't you think?

Try using the hosts file.
It's in C:\WINDOWS\system32\drivers\etc
OPen in notepad and put in this line as many times as you need.

127.0.0.1 Name of site to block

Once this is done the request for the URL will be loopbacked, hence blocking the site access.
Continue the same thing by changing the last number of the ip address

I think blocking inbound/outbound mail services is perfectly legitimate for any company and should absolutely be blocked. This is not the same as blocking HTTP mail (i.e. Yahoo, hotmail, etc).

Having SMTP services inside your company that is not within your management control is a big liability now-a-days. With the ever increasing use of RBLs by email administrator the chances of your company getting listed which affects your flow of email is greatly increased. For instance, improperly managed mail services (i.e. SMTP servers) can be used as a mail relay thus subjecting that particular IP, an entire block of IP's, or the domain that the IP originated from to be listed in the RBL's which will impact in/out mail for the company.

The easiest way to accomplish this is to block inbound and outbound TCP/25 except for your own mail servers. And the place to do it would be right before your ISP's connection on your side.

Hope that helps.

Casey