@0x4d6165 notmuch. The coolest "trick", but also curse at the same time, in my opinion is to store all mail locally. Combined with local #orgmode files this can become a reliable autarkic knowledge base. Following a reference to an email from inside an org-mode file will always work immediately, no network request needed. Curse, because it requires custom setup to load mails into the system, and to sync metadata (notmuch's tags) between machines.