Strange question, but I find a number of my clients like to correspond after the event. Once they've bought an item which they're happy with - normally a puzzle in my case, they're quite happy to send you back a snippet about themselves like: "I enjoy doing puzzles and normally sit with Tiddles on my lap doing them after watching Coronation Street.." So sweet, so you feel obliged to reply with a few lines about yourself, and before you know it, you've got a penfriend who'll happily natter away for hours.
I feel happy for them, because they've "met" somebody new. As long as you don't drop your guard by mentioning the fact that you're going away on the 6th. June for a week, I see no harm in it. Play your cards right, some dear little old lady might actually decide to leave you her collection of Capo Di Montes 
Although I say that in jest, sadly there are jackals out there who'll befriend the aged purely with that in mind.
The one thing I always do, is delete their messages for diplomatic/security reasons. What they say to me in confidence remains confidential. Do you correspond or do you find yourself too busy?
