Mailgun

I've used both Sendgrid and Mailgun at low/moderate volumes (150k mails per month) for transactional & marketing messages. Despite what I would consider roughly similar delivery rates I've preferred my experience with Mailgun. The biggest reason is actually the web dashboard - I just find working with Mailgun's website much faster and more clear.

That said - either service is a massive improvement on running your own infrastructure. If you haven't used a service like this for sending email you're definitely going to be impressed with how easy Mailgun will make your life.

We tried mailgun for several days. It took me 3 days to get the API implemented and another 2 days to get our application connected to the principals of this service.

After we started our marketing campaign we got an email after 1000 sent emails that our account has been blocked due violating some TOS.

This service is very strict so better look for an alternative.

A lot of different features which I (and a lot of users never will use). In this case it would be so great if there will be different versions of MailGun. Now, when there is no "sending emails for dummies" kind of tutorials I will use something more friendlier for starters users like MailerLite

Buuuut, 10K free emails per month is something I've never seen before!
Most of Mailgun clients don't even need to pay for sending emails.

10,000 emails free every month. No credit card required is a great deal for most small/midsize businesses. It also can integrate with WordPress. (https://wordpress.org/plugins/mailgun/)

Mandrill use to have a free level like mailgun