Setting of the font is stored in pmail.ini file (this file is plaintext so you can edit it e.g.in notepad)  which is usually located in mailbox directory you can check if changes are written there after switch off Pmail there or you can try edit in this file manually size of font.

Check if this file is not set as read-only etc...

You can also delete this file and Pmail recreate it, but you lost all user settings include POP3/SMTP definitions.

We are running Pmail 4.41 on two machines here. On my machine it works just fine. However, things have gone haywire on my wife's machine.

Pegasus is run in 'conventional' mode, not in the preview pane.

Every time she opens a message to read, the message font resets to 24.  Once the font has been set to 14, the next messages come up all right, usually (but not always) but once Pmail is shut down and restarted the problem reappears. We've tried any conceivable way we can think of, to persuade Pmail to save the setting for the reader: saving window size, exiting the program from the file menu, or from the windows control, but it just keeps coming back. I also noted when I've tried changing the view to the preview mode and changing the font size from there, the font sizes got garbled between sessions again. Furthermore, Pegasus keeps opening with the new mail folder in maximized mode. I have to close it and reopen it from the toolbar for it to behave civilized  and open in a smaller windowed mode. Again, this state does not save and reverts between sessions. 

Can somebody give me a clue how to persuade Pmail to start taking note of the settings we're trying to get it to use/save? Been using it since the early 90ies and it's never been this annoying before.

TIA,  -Peter