When you receive a personal email from somebody you've never met, out of the blue, should you send a reply? Politeness suggests yes. But what about replying to their reply to your reply? How long should an email conversation continue? When is it socially acceptable to abandon a shuttling email and not pen a response? Will the sender be offended if you hit 'delete' rather than 'reply' and shut the conversation down dead? These are tricky questions of modern online etiquette.
1) A personal email arrives out of the blue (↓) When a fresh email lands in your inbox, then you really ought to reply (assuming, of course, that it's from a real person and not an evil spamlord). It's only polite. Otherwise the sender may think that their email never arrived, or that you never read it, or even that you're deliberately blanking them. Even if you're not. People get paranoid like that sometimes. So it's right to reply.
2) Somebody replies to a first email that you sent (↑↓) You started this conversation and they've replied. Hurrah, they must have been interested in what you had to say. But should you chance your luck a second time? If you write back again, will this start up a wonderful online friendship based on common interests? Or will they just think you're a boring stalker? There are usually clues in their reply. If it's less than ten words long, stop now. If it's longer, and interesting, then a response is almost certainly worthwhile. But don't hit 'reply' if the email's too long. Five screens of rambling anecdotes suggests that the writer is either bored or obsessive, and you don't want to get trapped into a game of email ping-pong with them because they'll never go away. Delete the offending communication now before it's too late.
3) Somebody replies to your reply to their initial email (↓↑↓) This is going well. Having kicked off the conversation in the first place, now they've written again in an attempt to maintain the conversation. But is that what you want? It might be, in which case write back straight away. Alternatively, they may have misunderstood your first reply as 'interest' rather than 'politeness'. Don't feel guilty. Halt the conversation here. You have better things to spend your time on.
4) 5) The email exchange continues (↑↓↑↓) (↓↑↓↑↓) This is probably as far as most email conversations go. You've both said your piece, you've explored any repercussions, and that's probably all that needs to be said. It's OK to stop here.
6) 7) 8) 9) etc etc etc (↑↓↑↓↑↓) (↓↑↓↑↓↑↓) (↑↓↑↓↑↓↑↓) (↓↑↓↑↓↑↓↑↓) Sometimes the conversation continues. Back and forth, email after email, on and on. But at some point the conversation on this particular topic will come to a natural end. Either you'll fail to reply, or they will. No need to feel hurt. And maybe in a day or two, or a week or so, you can send them another email and start up another chat. Everyone's happy.
29) A lengthy dialogue has developed (↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑↓↑) Most email conversations have stumbled well before this point, but some never stop. By this stage it's got much more difficult not to send a reply. If you've invested this much effort in an exchange, you don't want to be the one who's seen to abandon ship. You might be replying out of a sense of duty, not because there's anything more to say. Let's hope not.
It's all so very complicated, isn't it? And if you disagree, I beg you not to send me an email saying so.