Bouncing and automatically replying to messages - Thunderbird
From MozillaZine Knowledge Base
While such settings can be seen as a bad idea (they open floodgates for Junk Mail, verify your address to spammers that they have reached a valid e-mail address and criminal elements can use the â€œI'm on vacation for the next three weeksâ€ information to pillage your residence), there are also many valid uses for such an automatic message in response to incoming e-mail. There are a couple of ways to accomplish this.
Through your ISP
This is the easiest solution. If you have your e-mail account through an ISP, you can usually set up such an automatic message through them. Normally this can be done through the ISP's Web interface, although your ISP may have another method.
Through a Thunderbird extension
This is a more difficult solution. TB New Filters is an extension to Thunderbird that provides â€œAuto-Replyâ€ functionality. However, this is not a filter for the beginning user, nor the faint of heart. There is no graphic user interface and the filters are created manually by editing a text file. Be aware that this extension is no longer supported. It is compatible only up to version 1.5.0.x
Through a new version of Thunderbird
Auto-Reply functionality has been available in the nightlies since the 2005-06-02 builds. Its also included in the v1.5 beta and release candidate builds. You can get them in the Thunderbird Builds forum.
Don't forget that the nightlies are for testing, are less stable and can have other bugs at this stage of development. The good news is that the functionality you are looking for should be in v1.5 and later. This is a solution for those who either want to be on the cutting edge or can wait for the next version of Thunderbird.