[Daiya Mitchell]

Yep, it definitely did. I tested it because I wasn't sure I wasn't just
repeating conventional wisdom either--and yeah, the header text showed
up under my return address, and the "single sheet of labels" pushed the
last row onto the second page.

Suzanne S. Barnhill wrote:
Well, the problem is that if you ever touch the header in Normal.dot (or any
template), you are left with an empty paragraph in the header, which one
would expect to interfere with labels, but when you use Word's built-in
label definitions, it uses its built-in magic to set the header/footer
margin to 0" and somehow suppress any error messages about being outside the
printable area, so I've always been curious about whether putting a header
in Normal.dot would *really* cause problems with labels (much less
envelopes). It's nice to have confirmation of what I was beginning to fear
was just superstition or an old wives' tale.