We are looking into this as we do not want to deliver soggy sandwiches. It looks like the quality of the bread itself is a big factor. Premium breads such as Rotelli have a well developed cel structure and just do not soak up the moisture like cheap brands. You can also make sure that meat or cheese is between liquids and the bread, but then you have the problem with seepage.
we wrap all subs in deli paper “dry waxed” and when they arrive they are still great…not soggy. I think wrapping in foil will always make your bread retain too much moisture. The subs go in a paper bag for delivery.
We did a lot of toasted and baked. A vented container (so many options out there) worked well. The restaurants competing for curb delivery for take out are really stepping up to the plate in this area. Check out a Ninety-Nine, Chili’s, Applebees.