This is the only email cleaning program that we use. This is mandatory if you are doing large amounts of emailing two new cold prospects. We have an extremely low balance rate from our emailing system. Clear out is our go-to program to do this and, without question, saves our email URLs for a longer period of time.
I haven't used many other email validation products before, only a couple of 'free' cloud-based options with limited list size capability. Kickbox is super professional, easy to use, and works.
I like Kickbox output files better as it includes the "domain". Overall, both softwares could do a better job cleaning lists. Kickbox shows more "unknown" emails where are BriteVerify shows less "unknown emails" but then more bad emails end up in the valid list. Kickbox has a higher threshold to put emails in "unknown".