Sidemail - The simplest way to send transactional emails. Sidemail makes sending transactional emails trivial, it's perfect for side projects, MVPs or the next big thing.
Mailivery - Reach the Inbox, not the spam folder.
Postal - Open source mail delivery platform, alternative to Mailgun or Sendgrid
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
WP Email Delivery - Managed email delivery for WordPress
Flowmailer - The email delivery platform you can rely on