Ok, what keyboard combo did I accidentally hit?
If you mean the space and linebreak stuff showing up, it looks like you’re using Word to compose your messages. In which case it’s “hidden characters”, accessed in Word by hitting the reverse ‘P’ in the toolbar. Not sure about when it’s pulled into Outlook, but try going View => Options and look for “show hidden characters”.
ETA: try the little down arrow on the right of the bottom toolbar. Betcha it’s hiding in there.
Found it. It was buried deep – Tools > Options > Formatting Marks: All – but I’m back in business. Thanks much!