A few days ago, @jack (currently the CEO of both Square && Twitter) posted a pic of his iPhone. [original tweet] It struck me as slightly surprising that both Square & Twitter could be using Gmail. Both companies have a ton of talent who deeply understand message delivery and message queues. I wouldn’t be at all surprised if both companies have people working there who worked on Sendmail or Postfix. On some levels, twitter competes with Google.. (if Google Pay …