A Royal Mail post box was stolen from Perry Green, Charlton, Malmesbury, overnight between October 14 and October 15.
A Wiltshire Police spokesperson said: “Please keep an eye out for suspicious behaviour around post boxes overnight.
“Anyone with information relating to this incident should contact Wiltshire Police on 101.
“Alternatively, you can call Crimestoppers anonymously on 0800 555 111.”