Let's say your laptop is where you keep Thunderbird. Let's say you set an auto replier in Thunderbird. Let's say you turn off your laptop. If you were to have set this in Outlook for an Exchange server, it would keep replying. This is because the server, not the e-mail client, does the replying.

You can do it with Thunderbird, but it won't happen when Thunderbird is closed. If you have Gmail, you can set a vacation autoresponder up on that server (but not through thunderbird, through gmail.com).

http://tbirdhowto.wordpress.com/2007/...

http://kb.mozillazine.org/Bouncing_an...