I like that it works in an automated way, so you don't have to do any work yourself - just wait for results! The price is also very reasonable (I think around $10 per 1000 emails). It could be easyer sometimes when sending multiple messages at once if there were different filters / settings available depending which email address we are trying send from etc., but overall this service has been great with our clients' inboxes getting cleaned up every month or two without having too much of my time taken away by them doing anything themselves as well :) Definitely recommend using Mailsigmaservice!! We use their software mainly because its free compared to other services out there who charge thousands each year instead of hundreds/thousands even though they offer similar functionality; however i can see how some people would prefer paying more than what msigs charges us monthly considering all those features.