I ran a kinda similar platform years ago I and I fully agree. It was a constant fight against blacklists, random spam filtering and weird attacks on my server l

I ran a kinda similar platform years ago I and I fully agree. It was a constant fight against blacklists, random spam filtering and weird attacks on my server looking for postfix missconfigurations. If I learned anything in that time is that email is not simple, and should be run by a qualified dedicated team, because there are so many pitfalls