On some broken email auto-responders
You have been referred to this document for one of a number of reasons.
- You are a "postmaster" or administrator for a site where
people use broken auto-responders.
- You are a list manager whose list members are getting auto
responses to things that they post.
- You are a member of a list, and have been getting pointless
and annoying auto-responders to your postings.
- You are a user who has enabled an auto-responder to your mail
and through your choice of broken software, got other list
members annoyed with you.
- You are ultimately responsible for some site which uses broken
software. That is, you are the boss of the "postmaster". You
may have played a role in the choice of the misbehaving
- You are just curious.
Although this document should be read by all of those people listed
above, its language is directed to the the postmaster or site
administrator of the site with the obnoxious auto-responder and to the
user who set it up.
Lists and courtesy
Consider a large email discussion list of say 1000 members. Now
suppose that at any one time 2% of the list members are "on vacation"
or "out of the office" or otherwise not reading their mail. Suppose
that they all incorrectly set up auto-responders saying so. That
would mean that every time someone posts to the list, they get 20
auto-responses from people that they probably don't know. Each
individual one is a minor annoyance, but collectively it would show a
great deal of discourtesy among email users.
Fortunately, since the early days of email auto-responders (from the
1970s), auto-responders have been designed to only respond selectively
to messages. Auto-responders and email discussion lists have been
living together without too much difficulty for decades. But the
advent of newer, less Internet-friendly software, has made this a
Proper auto-responders (among other things) shouldn't respond to
messages posted to mailing lists. There are several tricks that
auto-responders traditionally use to achieve this.
- They only respond to messages with a specific address in the
To: or Cc: fields of an email message.
For example, if I set up an auto-responder, I should set it so
that it only sends a response to mail that is explicitly addressed
to email@example.com. I could list
a handful of alternatives addresses as well to be responded to.
Most auto-responders do this by default.
- They look for list specific headers. Traditionally (though not
according to standards), many list management systems add a
Precedence: header to the message with the value
either being "bulk", "list" or "junk". While that convention
never made it into standards, there is no harm in an
auto-responder looking for such a header, and not responding to
mail with it.
- Look for a specific pattern in the sender information.
Traditionally (though again not formally) most email lists have
what is called an "envelope sender" in the form of
"owner-LISTNAME". Messages that have senders that begin with
"owner-" are very likely to be list postings, and so shouldn't get
"I'm on vacation" auto-responses.
Now, if an auto-responder does the above (or even most of the above) it
will not send off inappropriate messages in response to list postings.
Other criteria of a good autoresponder
There are other criteria of a good auto-responder, not all of which
are for interactions with mailing lists.
- An autoresponder should provide some indication of the message
it is responding to. I may post to several mailing lists and
send mail to many individuals. If I get an autoresponse with no
indication of what message it is response to, I am left baffled.
- A personal autoresponder should only reply once in some given
period (typically one week) to any given addresses. That is, if I
send several messages to someone who is on vacation, I only need
to get the auto-response once. This is actually extremely
important to help avoid autoresponder loops.
- An autoresponder should technically be an "error message". That
is, it should have a null envelope sender. This will also help
- An autoresponder should never respond to error messages.
Configuring your auto-responder
I have very little information about these. If people send me
information, I will try to add it. But basically, if you can't
configure your auto-responder to do the right thing, than either don't
use the auto-responder or don't join Internet discussion groups.
To meet some of the additional criteria of a good auto-responder, it is
easiest if the auto-responder is integrated into the mail delivery
system, but that isn't strictly necessary. And the main criteria for
list interaction do not require that.
- There are far too many versions of this Unix program out there
for much to be said consistently. But when you start the vacation
program you have to explicitly tell it which recipient addresses
matter for responses. Additionally, most versions of it that I
have seen pay some attention to the "Precedence" headers.
- exim filters
- If you are using exim filter files for auto-responders, there is
a macro "personal" exactly to determine if the mail meets various
criteria to be worth of an auto-response. Again, you need to
explicitly list addresses that need to appear in the To header for
a response to be generated.
Procmail documentation includes examples of how to set up
This appears to be the big offender. Almost all of the incorrect
auto response that I have seen come from such systems. These
typically are called "out of office" messages on those systems.
If someone can give me instructions on how to set that up so that
it behaves properly, I will include them here.
- Lotus Notes
I believe that this is similar to MS-Exchange.
- Novell GroupWise
I have been told that at least some versions of Novell/GroupWise
It may be the case that your site administrator has set up some
mechanism for setting up these auto-responders. Most individual users
may not be in a position to set up their own exim filters, procmail
files, or vacation invocations themselves. In all cases, users should
talk to their email site administrators about auto-responders. Well
managed sites will have guidelines and tools to do this which will
behave in an Internet friendly way.
The bottom line
The bottom line is that if can't stop your auto-responder from
responding to list postings, than either don't use the auto-responder
or don't belong to any lists.
Note that most the above discussion applies only to personal email
addresses. It may be appropriate to have functional addresses (such
as firstname.lastname@example.org which send an
auto-response to (nearly) everything. But those addresses should
never be on email discussion lists.
I haven't touched upon the debate of to which address an autoresponse
should go. Whether it is to the envelope sender or to one of the
headers. I consider that question a tough call, and people who argue
either side of that debate will still agree with the criteria I've
Version: $Revision: 1.5 $
Last Modified: $Date: 2003/08/13 18:17:09 $ GMT
First established: 2001/07/13
Author: Jeffrey Goldberg