I think it's sadly a bit of a chicken and egg problem, unless someone sets out to write support for servers (mostly dovecot I assume) and clients (web and desktop).
It would be worthwhile for many reasons not just the immutable IDs. I'd certainly donate to someone showing initiative working on this.
Emails should really be identified by Message-Id (which isn't guaranteed unique, but is very selective) and a hash of the body and a subset of the headers (e.g., excluding Received headers, and maybe using only Message-Id, Date, and From, maybe not even Subject).
A good email store is very searchable, and a good MUA searches email, and a good MAP gives the client temporary (ephemeral) handles for "open" emails.
>The external noise emitted by passenger cars has been controlled since 1929 when the Motor Cars (Excessive Noise) regulations were introduced. New cars are now required to meet Europe-wide noise limits. These have been progressively reduced from 82 decibels (dB (A)) in 1978 to the current limit of 72 dB (A) established in 2016.
Presumably you need to prove who you are to make changes to your record however. GDPR doesn’t give me the right or require a company to change a phone number if I call them up and tell them to change the number for some random name without proof of identity.
>1 The data subject shall have the right to obtain from the controller without undue delay the rectification of inaccurate personal data concerning him or her.
>2 Taking into account the purposes of the processing, the data subject shall have the right to have incomplete personal data completed, including by means of providing a supplementary statement.
