While "save as" works for email messages within Thunderbird (i.e., "save as" selected from the "More" drop-down menu on an inbox message), if I've saved a message (as an .eml file) in a Documents subfolder or on the desktop, and click on "File," the "Save as" choice in the File drop-down menu now (a) appears higher in the drop-down menu than it used to, (b) generates a side-menu with two choices, "File Ctrl-S" and "Template," and (c) clicking on the "File Ctrl-S" choice does nothing (nor does clicking on "Save as" in the three-bar (or whatever it's called) basic menu at the far right of the menu bar). File-->:Save as works fine for files other than .eml files (.txt, .doc, etc.).