Exporting multiple emails from macOS OS X Mail.app on 10.11 (El Cap): only PDF works.

An email search retrieved 100+ emails. I wanted to copy them to a separate folder for archival purposes. I know one can drag and drop a message and create a net standard ‘.msg’ format but when I tried that only worked for 1 message at a time.

Save As allegedly worked at one time, but when I tested both rich text and .mbox export they produced one large file that wasn’t very readable.

What worked was File:Export as PDF. That worked.