I don't remember the name of the email service but after setting it up for use by an app I was working on they got bought up by Mailchimp, who, as I recall told

I don't remember the name of the email service but after setting it up for use by an app I was working on they got bought up by Mailchimp, who, as I recall told me "you have to switch over to our service" which required re-coding all the email routines again. That was about the 3-4th time I had to do that over the years and after looking into their way of doing things that's when I decided to set up my own email server. I don't do mass mailing so that has been a good solution for me. Not great, but better than being stuck using a 3rd party service that can sell your dependence on them like an asset.