The code exists to read the user's word wrap width preference:
if (NS_SUCCEEDED(rv) && prefs)
// Let sanity reign!
if (width < 10)
width = 10;
else if (width > 30000)
width = 30000;
But the calculated width is never passed anywhere. In addition 30000 is a
very abitrary number, not supported by any of the RFC's relating to creating
plain text (text/plain) messages.
I have attached a patch that moves this code to a place where it can have
some effect, rationalizes the limits to match the RFC's, and allows
specification of 0. All this works perfectly with our without format=flowed
text. The existing issues with utf-8 are not affected.
Plese consider applying this patch.
*** This bug has been marked as a duplicate of 155219 ***