"Vacation responses" (also known as "out of office responses" or "away messages") are automatic messages that are generated by the mail server in response to incoming messages. They are used to inform people who are sending you emails that you are not available.
Microsoft Outlook has a simple interface for configuring vacation responses. Each user configures their message using the Outlook mail client, even though the Outlook client does not actually manage the vacation replies. Instead, Outlook uses its proprietary interface to the Microsoft Exchange server to make changes to the settings for the account. Therefore the Exchange server does all the vacation replies for the Outlook client, the user has a simple interface and everyone is happy.
Thunderbird, on the other hand, is based on open standards and protocols and does not have a proprietary interface to any mail server. Specifically, Thunderbird uses the open protocols of IMAP and POP. Neither of these protocols contain any reference to or innate support for vacation responses. Therefore Thunderbird has no simple way to communicate to the mail server that the server should issue vacation responses.
All is not lost however, as there are two possible solutions for setting up a vacation response.
Another option is to create a Message Filter and respond to all incoming messages with a template.
Table of Contents
Vacation Response Extension
There is an extension to the IMAP protocol for vacation responses. Some (but not all) IMAP servers support this extension. It is mentioned here because there is a Thunderbird extension called Out of Office which may (and we must emphasize may) allow you to communicate vacation response configuration from Thunderbird to your email provider's IMAP server. Unfortunately you will need to install the add-on to see if it will work. Alternatively, contact your ISP and ask if their IMAP server supports the sieve extensions and, more specifically, the Sieve Email Filtering: Vacation Extension.
Most mail providers provide a web-based email interface that can be used to configure a vacation response. We have listed the vacation response web pages for some of the common mail providers below. (Please help extend this list by adding the address of your email provider's page in the comments.)
See the AOL on-line help article called: Setup an away message in AOL WebMail.