I mean it's not that you're automatically blocked it's just that your server's score for sending email is nonexistent which means a high likelihood of being a s

I mean it's not that you're automatically blocked it's just that your server's score for sending email is nonexistent which means a high likelihood of being a spam server. You have to spend a long time to build up a reputation to get places to mark your email as not spam. This is why many providers that allow you to do bulk email through them have multiple IPs and they only let the most behaved on their better reputation IPs.