Is anyone aware if using all lowercase header field names in email messages
is ever known to cause any problems?
I don't know of a case where all lowercase fields was the proximate cause of a
problem, but I've seen cases where specific capitalization had to be used for
something to recognize a header field. I've also seen cases where fields had to
be in a specific order to work.
I've also seen problems with folding, especially when encoded words
were involved.
Of course all of this egregiously violates the relevant standards, and as much
pressure as possible needs to be brought to bear to fix the broken software
rather than attempt to work around it somewhere else.
Ned