This software does so much behind our backs it's ridiculous! There was no down side to us, but we could see what email address were being sent emails from after they have been checked as spam or clean (I know people complain about this feature). I use mailgun for all my mailing lists; there is nothing that i dislike in Mailverify aside of free plan limits you should consider moving over to AWS since your hosting needs are solved now with SES which cost more than $10/month per million messages delivered while gmail only charges like 15-20 cents. The best part is that it's free to use! It verifies your domain, its MX records, etc. I've used other services in the past but this one seems more reliable than others out there. Sometimes it takes quite some time (about 1-2 hours) until you get an answer back from them. If they don't respond within 24hrs then forget about using their service. They are very helpful when providing support or answering questions via live chat.