Open Tools/Options/Advanced/General/Config. editor and look at the preference mailnews.wraplength. The default is 72, but if you right-click, Modify, and set it to 0 (zero), the text in plain text composed messages should wrap to the window width.

Error: I still doesn't work. When I tested it, I just put in a row of repeated letters with no spaces and it ran the width of the window, but when I tried to Reply to a message with real words, it still cut the text into a narrow, newspaper-like column.

I checked the Config: setting and it is at 72.

Can it have something to do with the Plain Text/HTML setting of the incoming message?

Thanks,

Frank

It could be due to some non-standard formatting in the incoming message, but what is the effect, if any, of setting the preference to zero?

If the incoming message is formatted as HTML, your reply will be HTML unless your account setting is to send in plain text (Account Settings/Composition & Addressing). If the incoming is plain text, your reply format will depend on the account setting, as well as Send Options in Tools/Options/Composition/General.

I have HTML as the default account format, mailnew.wraplength set to 0, and in Send Options the Text Format box is unchecked, and the drop-down set to 'Send the message in HTML anyway'. Replies to any message always wrap to the window width.

The zero setting did it.

Thanks very much,

Frank