frogdog.io loves mailjet!
Mailjet is our go to solution for deploying emails from webforms. We use mailjet on almost every website we do for our clients who can't or won't provide their own SMTP solution.
Free! At least for our limited use case. Simple to setup and confirm new domains or addresses. Can manage multiple clients' needs through a single mailjet account.
The limitations on the free-tier account are fairly low (200/day), but its free so its hard to complain.
For our use case of simple transactional webform emails its simple yet feature-rich enough to fulfill the needs of our digital agency.
Simplicity and price.
Notification that a webform on a CMS based site has been submitted.
We no longer need to hassle companies for SMTP credentials.
Impossible to calculate, can't divide by 0. ITS FREE!
Give the free tier a try, you'll probably get hooked.