Overall Satisfaction with Mandrill
Mandrill is used 100% by our engineering department. Most everyone else probably doesn't know what it is or how it works, unless they've heard engineers talking about it.
Our use-case for mandrill is to send transactional e-mails to users as needed across our several platforms. Examples would be email invitations to resources in our application, forgot password/password reset requests, individual account updates and alerts, etc. We also use it to send higher volume marketing messages that are triggered by specific actions taken on our properties. Mandrill makes it easy to integrate to your existing software and send these types of emails quickly.
- Ease of integration.
- Availability of API logs and email send history.
- Email deliverability.
- The rate-limit system can be troubling. If you are switching providers and already have a large e-mail volume, you're going to want to transition slowly. The per-hour send limits are initially very low, and if you have any deliverability or complaint hiccups, they will plummet quickly. The Mandrill support staff is very helpful in this area - they will not (and claim that they can not) manipulate send limits for any account at any time for any reason.
- Billing is combined in with a paid MailChimp subscription, which didn't used to be the case.
- No free tier.
- If you already have a paid MailChimp account, utilizing Mandrill to send transaction emails is very cheap.
- Sending out emails to users at the correct times will boost user engagement and revenue, instead of relying on the user finding the information when they log in next, or relying on in-application notifications.
- The documentation and tools available for integration make adding Mandrill to your existing systems very quick, and inexpensive. There are plenty of open source and free tools to help this process along.
I don't have as much experience with Mailgun, but they were acquired some-time ago by Rackspace and Rackspace has a reputation for buying companies and not investing additional resources into them. So, at the time of evaluation (a few years ago) their feature sophistication was lagging behind Mandrill and Sengrid.
Mandrill has got a lot of features that most people will find perfectly adequate. Their deliverability is great, and their management interface (while not visually stunning) provides all the information and configuration options you're likely going to need. For these reasons, it's a good option for most people.
My main complaints have to do with how they changed their billing practices in 2016, removing the free tier, and bundling the service with a paid MailChimp subscription. If you're not already paying for a MailChimp subscription, there are other services that offer 12,000-25,000 emails, per month, for free.
My other gripe is the rate-limit issue. If for any reason users start complaining about your messages, your rate limit (number of messages you can send per hour) will be slashed dramatically. This is for a good reason, but the limits look to be very strict, and they have no issue with taking your account from 10,000 messages an hour to 150 messages an hour. This can absolutely kill a SaaS provider, and they are 100% unwilling to make concessions.