I have been using sendsimple to send out emails for some weeks now and it's the best you can use for cold emailing. It is very flexible and easy to use when compared to other cold email platforms.
I love the ability of not paying for hosting just like what is obtainable in sendy. Though they lack some features, I believe they'll be updating the app with more feature soon.
The founder is very active and I see some updates has been implemented recently.

Kudos