What are some alternatives?
When comparing Mailtrain and IMAP API, you can also consider the following products
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
Kill the Newsletter! - Convert newsletters into RSS feeds
Sendy - Sendy is a self hosted newsletter app that sends emails 100x cheaper via Amazon SES
Listmonk - Send e-mail campaigns from a powerful dashboard. High performance and features packed into one app.
MailerLite - Affordable Email Marketing Software. Get all features (Segmentation, Automation, A/B testing) for up to 1,000 subscribers & send unlimited emails for free!
Really Good Emails - A large collection of good product email design.