Please excuse me if this is already possible, but I haven't found a way to do it.
It would be very useful to be able to pass a message id/URL to aerc in order for it to open it directly, in particular for emacs org-mode integration (see an example for mutt there: https://upsilon.cc/~zack/blog/posts/2010/02/integrating_Mutt_with_Org-mode/
What kind of URL are we talking about?
Any way to open a specific email in aerc from another program would be great. Something like: message://server/unique_id
See the Thunderlink add-on for Thunderbird, which does exactly that: https://addons.thunderbird.net/en-US/thunderbird/addon/thunderlink/
Ideally, it would be fantastic if one could select an email in aerc, send it to emacs via org-protocol, create, for example, a new TODO item related to the email, and then be able to open it directly by clicking on its link in emacs to have it displayed in aerc.