> The company I work for has been around for 15 years and we spent the first 5 or so getting yahoo and live/hotmail/outlook to accept our mail reliably despite proper dns/dkim/spf
This matches my experience from roughly 10 years ago. Even with a non-residential IP address, correct SPF, etc, it took months to navigate the biggest providers' obstacle courses for whitelisting. After succeeding with those, plenty of smaller providers remained to identify and work through one by one. And then, every so often, an already-completed one would revert.
It was not impossible, but even for someone experienced in email system internals, it was a slog that seemed never to be 100% done. I don't expect it's any easier today.
This matches my experience from roughly 10 years ago. Even with a non-residential IP address, correct SPF, etc, it took months to navigate the biggest providers' obstacle courses for whitelisting. After succeeding with those, plenty of smaller providers remained to identify and work through one by one. And then, every so often, an already-completed one would revert.
It was not impossible, but even for someone experienced in email system internals, it was a slog that seemed never to be 100% done. I don't expect it's any easier today.