I got this Debian bug report: "For use in scripts that don't specifically use xdg-email, it would help to have an xdg-email option (or a separate program that invokes xdg-email) to read in an mbox-formatted email message (or more than one such message), parse the headers from the message(s), and invoke the user's MUA. - Josh Triplett" http://bugs.debian.org/427727
I suggest to create a separate script for that pupose that calls xdg-email.
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