Turns out I maligned Apple Mail for something I did. At some point I set up a Keyboard command to use ⌘V for “Paste and Match Style”. That prevented me from pasting or using TextExpander in header fields when composing a new message in Mail. 😊 I could Paste from the Edit menu.
Smokey Ardisson Seems strange to me that changing the keyboard shortcut messed up TextExpander; I would have thought it keyed off of the underlying Cocoa selector instead of the shortcut. At any rate, glad to hear you’ve figured out that strange pasting problem ;-)