I can totally echo this(running my email forwarding service [0]) so I deal with it at high email volume too. Outlook/Hotmail is kind of stupid in this sense: i

I can totally echo this(running my email forwarding service [0]) so I deal with it at high email volume too. Outlook/Hotmail is kind of stupid in this sense: if the first time, a new domain send an email they are very likely to flagged as spam. But if the user simply reply or send to that email, the moving forward hotmail won't flagged it. In other word, hotmail rely stringly - is this domain new? - is this ip address start to send email new? - if I interact with this sender in the past Seems thing with icloud and their proofpoint spam filtering. gmail in other hand, has the best delivery rate, clear error message, great rate limiting and cool down period. gmail is very smart, if we accidently send spam(due to our failure to filter out spam), gmail won't blocklist the whole IP, but hotmail/icloud does. And the process to delist from them homail/icloud are just absurb. I'm unable to contact their team. --- [0] https://hanami.run https://hanami.run