Without wanting to claim the hard work of others!! I would love to create an issue that tracks bumping Mail to ~> 2.6 for Rails 5 (e.g re-create a PR like this one). Here’s why:
Jeremyevan’s PR to use a text-based columnar storage in the Mime-types gem has been shown to significantly decrease memory when a user opts in to it (I’ve seen 20mb decrease personally). This memory saving behavior is a default in the 3.0 release of Mime-types (as well as a raft of other, really lovely changes). Given that Mail works with Mime-types 3.0 and when Mail 2.6.4 has finished brewing it’ll allow Mime-types 3.0 It would be great for Rails to nudge users to pick up this behavior too.
What are people’s views on this? It feels a little audacious of me to modify one line of ActionMailer’s gemspec but I’m really keen to see this change happen.