Questions and comments:
1. You probably know this already. Outlook Express uses IE to print, even for plain text emails. So, margin settings come from IE's Page Setup. When you adjusted margins, I presume this is how you did it. Correct?
2. What versions of Internet Explorer and Outlook Express are you using?
3. What is the make and model of your printer?
This may be a printer driver bug. The printer driver provides printable area information to the Windows application. Each printer has its own printable area. The top, left, bottom, and right non-printable areas vary for each printer, as does the horiz. and vert. dots per inch, etc. I have observed margin calculation problems caused by printer driver bugs for some printers. The app in question worked fine with all printers except for certain ones. Some/all Epson and Canon ink jets if I recall correctly.
Suggestion 1: Try to obtain and install an updated printer driver from the manufacturer. Perhaps this hypothetical bug is corrected.
Suggestion 2: Try to use a substitute printer driver. For example, HP LaserJet 4 printers can use an HP LaserJet 3 driver. If this workaround works, you can define a special printer icon with this other driver just for your Outlook Express printing and continue using your existing printer icon for all other printing.
Suggestion 3: Upgrade to the most recent version of Outlook Express and Internet Explorer. Perhaps the newer OE and IE work better with your printer/driver.
Suggestion 4: Change to another email client. Mozilla Thunderbird is free and works very well. I personally like OE but switched away from it some time ago out of security concerns.
I hope this is helpful. Good luck!
-----Steve Jackson
CEO
Software Corporation (Softcorp)
http://www.softcorp.us