In your home directory:
You should of course replace the message with your own message, but please make sure you have the "From:" line with your address (as well as "via the vacation program", which will help automatic mail filters at the other end avoid auto-responding to your auto-response) and the "Precedence:" line (because junk precedence is another way some automatic mail filters avoid auto-responding to auto-responses).
From: Your Name (via the vacation program) Subject: I'm on vacation! Precedence: junk I will be on vacation until July 23rd. I will answer my mail then. Yours Truly, Blah.
PLEASE NOTE: Some text editors, (such as pico, when called without the -w command-line switch) will probably wrap the From: line so that your email address is on the second line of the text. This will cause problems which make your autoresponses difficult to read for those that receive them, so you'll need to undo the wrapping, either by moving the cursor to the end of the From: line, and deleting the next character, or by starting the text editor in non-auto-wrapping mode. For example, with pico, you would type:
pico -w .vacation.msg
\your_userid, "| /local/paths/vacation your_userid"
\d_echtn, "| /local/paths/vacation d_echtn"
You will notice that there are two files in your home directory, .vacation.dir and .vacation.pag. These files will contain the addresses of people who send you mail to which "vacation" auto-responds. To see these addresses in human-readable form, use the dumpvac program. For more information on vacation, read the vacation manpage.
Finally, when you return from vacation, just delete the .forward file (or move it to a different name) to cancel the vacation program.