Hey kabes, I'm running into the exact same issues and posted almost the exact same Ask HN a few hours after you[0]. You're not alone! Eagerly watching this thread.

I'd also be curious to hear how I can make my system more robust in the face of these issues. Right now, Sendgrid reports these emails as "successfully processed" and so I don't have a good way to programmatically retry these jobs.

[0] https://news.ycombinator.com/item?id=24212202