What do you like best?
the fact that it lets the individual control what is spam or not and minimizes the junk that arrives into our emails system. this lowers our cost of storage and archiving. People like it and we have almost no calls about spam, I didn't get an email, lost an email, etc.
What do you dislike?
Getting data from proofpoint about how their system works and configuring as you want may take more time that you would like, but this is somewhat expected once you outsource technology too the cloud. It can't fix everything as we did have some successful phishing attacks because from proofpoints perspective the email was legitimate
Recommendations to others considering the product
One thing we learned is to make sure you quantify what you need for history of emails that do not come into your email system. We only allocated 7 days for the retention of stuff that does not get through because it was marked as spam, malware or virus. In some cases of a breach, you may want to do some investigation that might require looking past 7 days. They charge more to keep more longer, so consider this at initial purchase or you may have to add it later.
What business problems are you solving with the product? What benefits have you realized?
Many questions and help desk calls about spam, false positives, executives irritated by spam and not getting emails.
Benefits - We have minimized the email coming into our systems, people have a dashboard of spam they can pick and choose what is delivered, whitelisted, or blacklisted.