UPDATE: To solve the describe problem, you can follow their instructions.
WP Fastest Cache is a cache plugin which speed up your blog and can save a lot of resources. The plugin serves already rendered page to avoid the long and resource consuming initialization of WordPress on each visit, the activation of all installed plugins and finally the page generation by your theme.
A lot of work saved!
One of the optimization coded in WP Fastest Cache is the utm_* tracking parameters detection. Maybe you don’t know what they are, think about them as some additive information in your blog page URLs to track visits, conversions, campaigns and so no. Maybe you’re not using them at all!
If those parameters are present, WP Fastest Cache always serves the requested page from the cache, ignoring possible other parameters. That is a problem because other values may change the page content and behavior, as it happens for Newsletter action URLs.
The issue in this case is to have the tracked links inside your newsletters, when you use even the Analytics Addon, not working anymore. But generally if you have something adding utm_* tracking parameters to your URLs they may not behave correctly.
At this time we have not a solution, but we contacted the WP Fastest Cache plugin author to define how to solve that problem.