Since any mail can be found under the All label by definition the
simplest solution is extracting the message id from the end of
the current url and then creating a new url pointing to All.
This URL should always work unless the mail is deleted:

https://mail.google.com/mail/?shva=1#all/<msgid>


So this would work too:

#+LINK: gmail https://mail.google.com/mail/?shva=1#all/

[[gmail:1331f3490dff1205][conversation about gmail links]]

Too bad I have set up Emacs to use emacs-w3m, in which this does not work -- probably the hash part is handled by client-side JavaScript.


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