In 1985, a 13-year-old girl in New Zealand spotted a pair of purple, lip-shaped sunglasses in “Young Miss” magazine. In March, I traveled 9,000 miles from New Hampshire to deliver them to her, finally fulfilling my pen pal’s decades-old request. International Youth Service, the agency that matched us up 40 years ago, has long since folded, but other pen pal programs have survived — or even began during — the internet age. And even though New Zealand's postal system has reduced home delivery days, Denmark has stopped delivering letters altogether and Canada is moving in that direction, some see signs of a letter-writing resurgence. “The hunger is there,” said Rachel Syme, a writer for The New Yorker magazine who created a pen pal program during the COVID-19 pandemic and later published a book encouraging others to take up handwritten correspondence.…