Mailgun still didn’t automatically rotate DKIM keys last time I looked, otherwise I’d rate them much higher. That one thing creates a detail I don’t want to have to worry about.
Not only do they not automatically rotate them, there's no functionality to manually rotate them either. The only thing you can do is delete the configuration for your domain entirely and recreate it, which of course nukes your Event log. Hopefully they are working to address this...
Besides, their technical skill is pretty poor when their site shows "page not found" of some sort on log in process for a split second and when you try to search through the logs, they will quickly show you that I've made excessive access after less than 10 searches.
They had an incident on themselves and I asked them to resend the emails that they failed to send and support couldn't do that and that got us off of SendGrid.
Large free plan limit is the only good part about SendGrid.
This is typical of single page apps. They have a default state of "no data" and then they update it when they get a response.
It seems SES or mailgun are the primary options these days.