OK, so by "immutable" you really do mean "static" then? Static stuff can change, but stays unchanged until you actually change it. Dynamic stuff can change even without input from you. Mutable stuff is possible to change. Immutable stuff is impossible to change. etc.
The bigger issue though is I'm trying to square what you're saying here with your blog post:
> I admit it annoyed me when I first ran into it – why can’t you just fix up a message in place
If this was a poor wording, maybe go back and rephrase? Because I it seems pretty undeniable that after reading this sentence the reader gets the impression that you claim it's not possible to go back and fix up a email in your own inbox. Which wouldn't really matter, except that people who aren't aware otherwise will actually believe you and spread misinformation on this. Last thing I want is someone reading your blog post and falling for a scam because they read from a presumably reputable source (you) that emails can't be edited post-facto.
Once you send an email to someone, you can't change it. It's that simple.
It has absolutely nothing to do with what you can do to your own inbox. The entire point is that you should be able to rely on the fact that what you see in the emails you receive from a sender cannot be modified by that sender.
If someone sends you threats over email, you just archive them as evidence. Now with amp, they can send you threats that only show a threat the first time and then load inane text the rest of the time.
I'm sure someone thought this was a good idea but I can't imagine they used emails very much themselves because this is idiotic. Email isn't a web browser.
There are tons of games you can play with email. If it isn't signed with PGP or S/MIME or DKIM someone on either side can make it look like something completely different than the original.
A bad actor can claim their edited copy of your email is death threats.
Emails are immutable, mailboxes are mutable - but only by deleting and writing a new email. Sure it can be similar to the previous email because copy and paste exists - you're not hand scribing it. But the fact remains that for the mailstore, this is a brand new message minted out of whole cloth. You can't edit in place.
And in terms of how our own servers work - there is a backup of the old version, because it was a separate message in its own right that was deleted by the action of making a new message and deleting the old one.
