Related Clues:

• Writing pair
• Foreign correspondents, perhaps, enclose a line in addition to note
• Quiet nerds, fine when mixing — writers, rather than talkers?
• Young correspondents make newspaper proprietors initially burst into lots of laughter
• Friends you may never see
• One addresses one's remarks to them
• Correspondents who write how swans accept mate
• Some foreign correspondents
• Friends who may never meet
• Friendly letter writers
• Recipients of foreign mail
• Those in a certain long-distance relationship
• Letter-writers' enclosure with note has one in tears
• Snail-mail correspondents
• They correspond with a line on page tucked into enclosures