I've done some more testing and sent you a separate mail intending to include some attachments from Outlook, but then I realized I lost the original "Outlook.pst" file that had the attachments I sent you back in January when I changed computers. And it's taken so long to do this newest testing that I wanted you to first see what I found out first and maybe the Outlook stuff you can create more usefully yourself or it might not be necessary. So I'm posting here what I sent in my mail:
I narrowed down the missing-line-breaks problem to where it's now easily repeatable (for me, anyway).
*** First of all, it seems to happen only on emails that originate from Yahoo Mail. If I create the mail in Aqua Mail, there's no problem -- then I can reply to it from either Yahoo Mail or Aqua Mail and the line breaks are always retained.
Also, there's no problem if I reply to a mail I haven't originated in Yahoo Mail that came from outside.
*** Here's how I see the problem:
I tested by first creating and sending a mail to myself from Yahoo Mail (3 lines of text separated by line breaks). When I replied to this mail using Aqua Mail (another 3 lines of text separated by line breaks), that 2nd mail is received in Yahoo Mail without line breaks (only affects the newest text -- old text is unchanged).
However: that 2nd mail shows up in Aqua Mail with the line breaks intact. Did you get that? I see the same mail in AM with the line breaks there, but without breaks in YM.
If I only ever reply to the 1st (original) mail using Aqua Mail, the problem never shows up if I only look at subsequent mails in Aqua Mail. But, open up Yahoo Mail, and all the newest mails sent from Aqua Mail will be shown without line breaks.
Again, a mail originally created by Aqua Mail never shows up without line breaks in Yahoo, even after doing several replies to yourself back and forth in either YM or AM. The mail seems to have to be created in YM.
Also, any mail replied to using YM will also be ok -- line breaks always intact, though this never fixes the old mails further down the page that came from AM.
*** Bottom line: originating a mail in YM will cause subsequent replies from AM to lose line breaks when the mail is viewed in YM and will stay lost if using YM to reply further, though the new text created in YM will be ok.