Possible Clues:

• The final blow is that's no more mail
• No more mail, and no more light, when that's blown
• It sounds of late as if there'll be no more mail
• Final position held, call in the army
• For late people and late letters, by the sound of it
• A final collection and announcement of retirement
• One's calling observed immediately prior to retirement?
• Survive job getting military farewell
• Collected by a man of letters - of late, it's played as a sad reminder
• There are no jobs to be had after this call for retirement