email security for on-premise exchange server

Security is a vast topic. I have done several security audits for mail servers. It is a complex and expensive solution. Your security starts from client (app, permission and OS), server(app, permission and OS), network, firewall etc. You also need product to audit your environment regularly.

For 25 users, i would advise you to look for office 365. There you get security by default.

exchange plan  on office 365, select the one you would like to use, online exchange has all the features of on premise without the need for hardware. its great for small business upto 40 users.

We have to host the email server on-premise is the requirement ( cannot have it on cloud), please help with email security solutions like cisco email security appliance or any other products. thanks.

it depends on your budget, and how much control you want locally.

thank you one and all for the inputs it is very much useful. received call from microsoft exchange server technical resource and informed that if we go for exchange enterprise we do not require to go for third party spam firewall and virus firewall the exchange enterprise itself has firewall feature, please suggest.

i would always use a third party anti-spam / anti-virus solution, the reason is that with the exchange solution you have make sure its up to date and working correctly, also the mail has already entered the exchange farm before you can scan it, with an external solution in the DMZ it can be scanned before its past to the exchange servers, why are you paying for the enterprise version, do you require all the features, if not look at standard and see the cost difference and apply that to a new on premise spam filter or best option use a cloud based solution with your local on premise solution, 2 layers of protection.