Case updates via email question

We’re trying to implement a system that will make case thread updates when a unique email address is either in the To or Cc line. It works 80-90 percent of the time, but occasionally does not update the case, which is problematic. We have been advised by our developers that it’s most likely related to emails only being refreshed in 1 minute intervals.

Does anyone use this functionality and have been able to make it work 100% of the time?