如何在Comet聊天中避免死信息？

I am doing Comet chat with Erlang and PHP. But now I think I met a problem: the polling connection will disconnect and reconnect automatically in about a certain time (I set this with 10 seconds), so there will be a period of time that the user doesn't connect to chat server. If a user send message at that time, the message will be dead (no one could receive it). I am doing Comet chat with Erlang and PHP. But