Possible Clues:

• Post up?
• Put on the radio, say, man on the radio offers news from overseas
• Communication from one who should inherit (masculine), so it's said
• Strain with money trouble in post overseas
• Correspondence on the up?
• 'Par avion' letters
• Letters dispatched in fliers
• Trouble about girl’s high-flown writings?
• One inheriting man’s sound sort of post
• Letters announcing successor is a man