It's easy to use, it's fast, and it has a lot of options for different types of email addresses. I like how it's able to work with both gmail and yahoo accounts. It didn't have any features that I disliked, but there were a few things I would love to see added in future updates. If you're looking for something simple and reliable, this is it! We've been able to identify email addresses that don't exist or are invalid, and we've been able to send emails to those addresses without sending them to our spam folder. I like how easy it is to use. I also like that you can have many different validation rules set up for your lists. It's very helpful in preventing spam and junk emails from reaching your customers. Nothing so far, but I do plan on using this product as my main email validation tool. If I ever did run into any problems with them, they are quick to respond and help out. I highly recommend SafeToSend! We are solving our SPAM issues with SafeToSend and we haven't seen any negative effects yet.