More often than not I end up talking to someone in the sender's IT who fancies themself an expert and is completely incredulous that there could possibly be a problem on their side ("But we don't have problems sending email to anybody but you...")
I should want to fight the good fight, but it's so demoralizing.
Edit:
Dealing with other IT people on problems like this taught me a ton of humility. It wasn't until I was in my early 30s before I'd reached a level of maturity to approach trouble reports like this being reported to me with an open mind. Before that I fancied myself and expert and, likely, was insufferable in many contexts.
Now I'm insufferable in fewer contexts.
Only half joking. If you can't figure out SPF/DKIM then you should find a new job.
I've had more than one argue with me that having more than 10 lookups in the SPF isn't the issue even though I am showing them the SPF failure and the RFC stating that you are not allowed more than 10. Like, good for you that Gmail doesn't care, we do, fix your shit.
When I learned about this during the post-mortem I was incensed, to say the least. Email mgmt is part of a professional’s job, for better or worse. Accountability for that doesn’t suddenly evaporate because of a scenario like this. I don’t practice zero inbox for fun. I do it for my sanity and effectiveness. Technology can’t magically solve every problem.