GMail may not use public blacklists, but they definitely have IP-based reputations that feed into other blacklists. Just a few years ago, I personally experien

GMail may not use public blacklists, but they definitely have IP-based reputations that feed into other blacklists. Just a few years ago, I personally experienced this sending email between two GMail accounts, and then I noticed that my (workplace!!) IP address ended up on a public blacklist within an hour. Fortunately I noticed fast enough to get it removed before any mail delivery was affected.