St. Patrick's Day became a thing in the 17th century to commemorate Christianity's arrival in Ireland and the saint's death on March 17th. (See a pattern? 17th century, March 17th...maybe we're just making something out of nothing here with the numbers.) St. Patrick's Day emails throw on their best shades of green to celebrate Irish heritage and culture with feasting, merrymaking, and holiday discounts. Show your customers to the pot of gold with the VIP treatment of personalization.