Mailing manuscripts

Large padded envelopes can be found at Office Depot and Office Max.
I've ordered them and mailed a 575 page manuscript from Germany with much success--AND had the monster mailed back without envelope tearing. They're made to be put through the ringer.
From all the latest that I've read, you're right: they hate those boxes.
The #1 reason? You can't stash a box in your briefcase to take home that night. As the carrier of a hobo bag, I can totally relate to this. No matter the size of the bag, if I can fit it in my over the shoulder hobo bag, we're good.
If not..eh...not so happy.

Just be sure that your friend uses the PADDED envelopes. Great big yellow monstrosities. They rock!

Hope this helps.

Oh,
PS
Rubberbands not necessary, and most hate 'em. They like the pages to be be free.