It used to be that Yahoo Mail messed up my returns. I use "Plain Text" mode, and I put two returns between paragraphs. It used to come back to me with what looked like four returns (ie, one CR/LF pair getting translated to two CR/LF pairs). However this was apparently only in the mail copies I cc'd back to Yahoo, and not to the mail send to others, so that was okay.
Now Yahoo Mail has changed to where all the multiple CR/LF pairs are changed to one CR/LF pair. This is annoying because all my paragraphs end up smushed together and it looks awful.
I've played around with switching to Yahoo Mail Classic but it's just a pain to use with any efficiency. Now I'm using HTML mode and I'll see if it's any better. But it might be time to switch to something else, like Gmail.
