I suspect users on my network of using a web mailer but you don’t know which one is being used. This is against Company Policy and I want to be able to track these web accesses. My network does not have a proxy in place. How can this activity be detected.
If you access the Web :: Top Websites report which can be found under Plugins->Web->Top Websites
Fill the Website Name filter field with a simple search string of mail.
Click View and the accesses to all such sites will be displayed for example this will highlight usage of gmail and yahoo mail. By expanding the filter to include other known sites the report can be improved.
Once you are happy with the filter you can save the report for future use by selecting More Actions -> Save Report. This will allow you save this report as a Custom Report rather than having to regenerate the filter.