The Danbury Mad Hatter Chorus will continue its tradition of delivering singing valentines this year. On Tuesday, Wednesday and Thursday, February 12 through 14, barbershop quartets wearing black tuxedos and red bowties and cummerbunds will ring doorbells, pop into offices and show up at restaurant tables to sing “Heart of My Heart,” “Only You” and other romantic classics for wives, husbands, sons, daughters, beaux and sweethearts. Anyone can hire a Singing Valentine to be sung anywhere in the greater Bethel area for a $49 donation.