I kept finding references to "the envelope sonnet" but I wasn't sure which I had meant. Just now I found it. February 2005 paper journal. It's... wow.
an Envelope Sonnet
A feather touch quills each soft, careful line
Each letter caressed with slow, conscious care
Adorned in serif, but with meaning bare
Though posed for you behaved, contained, confined
Behind the words, a hushed ardor retreats;
Beneath each phrase, my roiling hungers sink;
My uninvited longing sighs as ink
in strokes across the grain of smooth, calm sheets
Restraint is in this poem I write for you
That won’t be copied in digital font,
But do you guess how my desires rage
When my tongue slides along the strip of glue
And tastes the defined edge of this sharp want
Caught in the folding of a paper cage?