I need some help with EOP's "ASF settings in anti-spam policies" settings as we have "standard" option set up so it is auto turned off. Now my questions is if I turn it on then is there any chance that I may not receive legitimate emails as the protection becomes much strict or can I enable some features which won't have major impact on the environment. Any suggestion would be appreciated.
Yes, there is a chance you will increase the number of false negatives. Use the advanced settings sparingly, and only as needed. You can run most of the settings in Test mode, in order to preview what effect they will have.