I originally settled on Kickbox because it would help me kick out undeliverable email addresses from lists generated by my IT department before they generated a hard bounce in my marketing email system, potentially flagging me as a bad actor. Getting Kickbox set up with HubSpot was a breeze and definitely achieved my initial goal. Since them, my Product team has leveraged the Kickbox API in our product, stopping people from entering undeliverable email addresses during the product sign-up process. Review collected by and hosted on G2.com.

Kickbox generates a fair number of false undeliverables...email addresses that work just fine for one-to-one communication but which reject mass mailings. Be careful the extent to which you implement the tool Review collected by and hosted on G2.com.