> Delivery to gmail and hotmail/outlook accounts is becoming a game of chance.

I haven't had any issues recently, but wonder... Are the failures still well-noticeable? I mean, when Gmail/Hotmail reject the letter - do they do it properly (SMTP 4xx/5xx rejection) or maybe they're now silently discarding it?

When I had the issues (even with large mail providers), my MTA had always generated me a bounce, and it had always contained something sensible and immediately useful - like a message that my DNS records got messed up or IP got in a blacklist. Every error message I saw contained links or clues to how the delivery problem could be resolved. Had this changed?