Post Office Resupply

Hi everybody
I'm going to be hiking the LT starting in late June.I bought a dehydrator and plan on making lots of dried fruits, dehydrated rice, noodles, etc. My plan is to stop at post offices/pick uppoints in manchester, rutland or the inn at long trail, jonesville and johnson. I am, vegetarian so ifigure this will be easier than finding all my stuff at stores. I have, however, heard that it can reduce the flexibility of my trip. If i send boxes to these places do I have to pick them up the day they arrive or will they hold them for a few days? Any advice regarding resupplies would be wonderful

Call the GMC.

At least Manchester and Rutland have supermarkets (not as fancy/large as a Wegmans, more like a ShopRite/Acme/Superfresh - I think most of those brands might be familiar to you based on your location) if you prefer to shop locally.
Manchester has Shaws (which is an Acme cousin) and Price Chopper (this one is a bit smaller sized), while Rutland has (I think, anyway) Price Chopper and Hannaford, maybe still a Grand Union? I don't know about the other two towns you listed

As to mailing - I think post offices usually hold items for up to 30 days, and other locations probably would, but generally the recommendation is to call each place you wish to send to (outside of post offices) to find out their specific policies.