This July 1, 2014, file photo shows a Moscow Mule made with ginger beer, fresh-squeezed lime juice and Hammer + Sickle imported Russian vodka in a copper cup at Anneke Jans in Kittery, Me. The popular drink has attracted internet attention after Iowa state officials issued an advisory reminding restaurants and bars they may not serve acidic drinks, including the popular alcoholic beverage, in unlined copper mugs.

This July 1, 2014, file photo shows a Moscow Mule made with ginger beer, fresh-squeezed lime juice and Hammer + Sickle imported Russian vodka in a copper cup at Anneke Jans in Kittery, Me. The popular drink has attracted internet attention after Iowa state officials issued an advisory reminding restaurants and bars they may not serve acidic drinks, including the popular alcoholic beverage, in unlined copper mugs.