Snail mail has taken on fresh resonance in this period of isolation, grief and unrest. Sympathy cards are selling out as the coronavirus’s toll continues to rise. Constituents are mailing in primary election ballots and addressing handwritten notes to local officials with compliments and complaints. (In some cities, they may also be sending letters to the police.) Many more are writing postcards to friends and loved ones, and calling for the United States Postal Service to be saved from its dire financial straits.