The command
reftex-citation can also be executed outside a LaTeX
buffer. This can be useful to reference articles in the mail
buffer and other documents. You should not enter
reftex-mode for this, just execute the command. The
list of BibTeX files will in this case be taken from the variable
reftex-default-bibliography. Setting the variable
reftex-cite-format to the symbol
locally does a decent job of putting all relevant
information about a citation directly into the buffer. Here is
the lisp code to add the C-c [ binding to the mail
buffer. It also provides a local binding for
reftex-cite-format.
(add-hook 'mail-setup-hook
(lambda () (define-key mail-mode-map "\C-c["
(lambda ()
(interactive)
(let ((reftex-cite-format 'locally))
(reftex-citation))))))