Mail double spaces the quoted text of a reply

Just chiming in to say that I've been experiencing the same thing. The extra spaces seem to be at the points where the text "wrapped" when I originally composed the message. It doesn't occur all the time, and it doesn't matter if the reply is coming back to me from someone else with Mail.app, Outlook or any number of web-based email services.

I hope my original messages aren't being displayed to the recipient like this, 'cause it'd really make me look like an idiot!

Mac OS X (10.4.6)

I'm also experiencing this wonderful "feature." If anyone has any ideas??? I've tried changing styles, fonts, nothing seems to work except to copy style (cmd-shift-c) from something normal and then to past style, OR, you can copy the original text and then paste it into a reply after deleting the "quoted" text. Not really what I expect from Apple!

Hmmm, I am looking at the beginning of a reply to an email, and I only see the double spacing at the change of a paragraph, which is the proper format when sending letters. The paragraph proper is single spaced, but the double space occurs at the change of a different paragraph.
Paula

iMac 1.9 GHz PowerPC G5 1.5 GB DDR2 SDRAM Mac OS X (10.4.6) Slot Loading 8X Dual Layer SuperDrive, iSight & Apple Remote; iPod Video

when you get a mail that does this (most often it's from an aol email client user in my experience) before replying switch to the plain text version of the message, then hit reply.

View -> Message -> Plain Text Alternative