Oh, now I see the "+" signs here at work using Outlook. So it must be mail client preference or something. Before, at home, I was using Gmail.
I found that there are three values for the enctype and that w3schools defines them as follows:
application/x-www-form-urlencoded - Default. All characters are encoded before sent (spaces are converted to "+" symbols, and special characters are converted to ASCII HEX values)
multipart/form-data - No characters are encoded. This value is required when you are using forms that have a file upload control
text/plain - Spaces are converted to "+" symbols, but no special characters are encoded
So it seems the first and third will definitely put the "+" symbol for spaces; but the second one doesn't say that, though when I use it, it seems to do the same thing (ie. puts the "+" symbols for spaces).