Hey Folks, The issue reported here is linked to App Engine and Gmail tightening up their spam filters. The root cause was an increase in organizations sharding out their spam systems to utilize App Engine’s free tier in such a way that is (a) in direct violation of our ToS and (b) making all of our lives suck a bit more (raise your hand if you want spam). It’s unfortunate that while App Engine is trying to provide a…
Long time App Engine user here. If you're sending email as part of your app, I'd recommend using Mailgun (or similar services). You can set up DKIM, inbound routes, etc, and generally have more control over how your mail is processed. I never got the impression App Engine really wanted to be in the email delivery business, so if that's important to you, there are tools that are focused on that (and free up to a month…
The best part for me when using it for customers has been the bounce/click through rate tracking. When someone asks me, "how do I know they got it?" It's incredibly nice to point them to the dashboard and show a less than 1% bounce rate (people putting in bad email is almost always the reason) with a log of every single email sent.
Most my clients get this service for free because their volume us low enough. They have quite a generous free tier.