Well, I've been running my own mail servers for years, and I can tell you that getting Google and MS to handle your mail fairly is very challenging. There is m

Well, I've been running my own mail servers for years, and I can tell you that getting Google and MS to handle your mail fairly is very challenging. There is more involved than what you mention, and many posts here on HN have discussed that. There may be open standards, but Google and MS only want to interoperate with other big players. They don't want to bother with small fry.