We are webstudio that create sites for our clients. Websites very often need to send email-notification. Mailgun saves us from mail delivery headache. Also we have an web application that need an ability to route inbound emails with attachments - mailgun do it perfectly fine.
I like the email verification service that comes with mailgun. With this, I am able to verify if an email address exists before sending the mail and whats more cool is that mailgun offers 100 free verification every month. I like that the email template builder makes it easy to build email templates that work across all major email clients ensuring that clients get the same experience no matter which email client they use. We are using mailgun to send verification emails to our clients, we also use it to send transnational emails and the email template builder is just awesome. We are benefiting from the many features mailgun offers such as email verification, and the template builder which makes it easy for us to build custom templates.
I am building my own SAAS and helping other people build SAAS products. Mailgun has become my go to email sender for the simple reason the API is really easy to work with. Setup is easy and the support team have never let me down. I really like how easy it is to use Mailguns API. It works really easy from me to get my SAAS apps sending transactional emails, everything from confirm your account to sending them stats. I've also used mailgun in other SAAS companies with great ease and quick setup. Support has always been there when I needed them.