How do you double space emails on gmail?

Does Google de-duplicate emails across GMail accounts to save storage space behind the scenes?

• So let's say 1000 people get the exact same email from a source. That email could be like a "newsletter" or a Groupon, etc. I'd imagine since those emails are all identical and immutable, Google servers really only need one copy, with 1000 references to it. If a user replies, they can take a copy of it and include it in the reply. Such a technique could save their servers petabytes of storage, and it's not really rocket science (many VMs and compilers implement this technique for strings on the client side already). Furthermore, if the email differs slightly, where it might say something like "Hello Amir," vs "Hello Mike," I'd imagine the whole email could be stored, with a small diff applied on top of it for each of the 1000 recipients. I'd love to learn about how they implement this under the hood, and further how search is built on top of it so that said diff-application doesn't interfere with searching. ... just curious.

• Answer:

  First of all, for newsletters/marketing emails, nowadays most likely there is a tracking pixel added to the html body so it can uniquely identify the receipt, that cause each email can not be exactly the same. Secondly, marketing emails are mostly sent separately, so there is no easy way to Gmail to know the potential "duplicated" emails could be the same. Doing diff on emails html body is also VERY expensive. So I don't think Gmail would ever want to try to think about that, not worth it.