IPQS

I was very impressed with how easy it was to integrate IPQS into my existing projects. I thought it would have required more work to get it incorporated into the business logic but it was relatively quick and took less than an hour. As for saving us money, it has exceeded our expectations in that regard. I was using another service but it was about 3-4x expensive and was about 10-25% less effective.

There's lots to like about IPQS, but I think what I like most is that (1) it really does a good job of getting bad data out of my contact list and (2) it gives me the kind of detail about the data I need to make decisions about it. For example, IPQS gives me a breakdown of email addresses that are actually invalid vs. the ones that have a higher likelihood of being spamtraps or come from disposable email services. Plus, it allows me to choose how aggressive I want to set my filter in case I have good reason to believe certain email addresses in question are actually valid.

There are a lot of options -- which is one of the services biggest strengths -- but it also means there's a little bit of a learning curve. Also, I'm not sure that the list of my previous batches should be listed in a dropdown menu since that can get pretty long. Still, that's a pretty minor complaint.