Snail-mail correspondents

• "84 Charing Cross Road" correspondents, e.g
• Friends you may never see
• Distant friends
• Long-distance friends
• Exotic stamp collectors, maybe
• Long-distance correspondents
• Rings round newspaper proprietors at first for correspondents
• Recipients of foreign mail
• Friends by mail

Wiktionary Word definitions in Wiktionary
n. (plural of penpal English)