Two ideas--it could be for putting ice in the old ice boxes (the original refrigerators), or for the milkman to deliver milk. I remember our house had a metal chest on the front porch for milk when we moved into it in the early '60s--milk was still delivered that way for a while in the country.

Hi. Seems like I remember somebody mentioning such a door in another thread on here. It was used by the iceman who delivered the blocks of ice for the icebox. And maybe by the milkman too, I don't recall that.

I'm sure someone else will come back with a link to that other thread, or you can do a search on this forum to read the entire discussion. I have no idea if it is a lead lining or a zinc lining. If you need to know, pick up a lead test kit somewhere and find out.

It might attract pests to store compost in it. I know the raccoons find my compost irresistible so I'm happier if they're clawing at my compost bin outside than at my house. Not to mention rats and skunks.

KarinL

Nope it's a "cold box" used to keep stuff like milk and cream and butter and cheese in....warmer than the ice box and more easily accessable...in the years before that the common place was the window sill...for butter and cream...but you have an "up scale" version of the windowsill.
those that I have seen were lined with...tin? maybe? I was a kid and didn't anylize the metal! LOL!
Linda C