MailTemplate is an elegant program that does automated e-mail responses.
MailTemplate automates and streamlines the process of composing e-mail messages. Using predefined templates with embedded macros, MailTemplate dramatically reduces the time involved in both composing replies and new e-mail messages.
If you ever have any kind of e-mail you send on a repeat basis, you'll benefit from MailTemplate.
Free to try. Requires Mac OSX 10.2+ and either Entourage or Mail.
MailTemplate [via 43 Folders]