> Sorry about all of the duplicated e-mails. I had my Notes administrator
> create an Agent to forward all incoming e-mail (which included the
> isp-tech list) to another e-mail address. Apparently the agent was
> not written correctly and was also copying all CCs (which included
> linux-net@vger.rutgers.edu) and resending which caused a nasty loop
> of resending and resending!
[This message is directed at anyone who may at some point be
responsible for maintaining a mail server. It isn't intended to be a
flame towards the person whose message got duplicated repeatedly.]
Note that email should *never* be forwarded based upon the contents of
To:, CC: etc headers. Nor should error messages be sent to the
contents of From:, Sender:, Reply-To: etc headers.
It won't have just been CC:s that were the problem in this case. Most
of the To: headers in messages on this list contain the address
linux-net@vger.rutgers.edu.
The only address which should be used for forwarding mail is the
envelope recipient (the address in the SMTP `RCPT To: ...' command).
An exception is the X-Envelope-To: header when re-transmitting the
contents of a multidrop mailbox, as the X-Envelope-To: header should
contain the correct envelope recipient address.
The only address which should be used for sending errors is the
envelope sender (the address in the SMTP `MAIL From: ...' command).
Furthermore, whenever email is sent automatically, any existing
Received: headers should be preserved. This should ensure that any
routing loops which do occur eventually get broken.
It should be borne in mind that, whereas an HTTP or FTP server only
sends data in response to an explicit request from the recipient, an
incorrectly configured mail server is capable of spewing vast amounts
of junk into people's mailboxes. And there may be no way for the
recipient to stop it without blocking the messages which they do wish
to receive.
Fortunately, the Internet is currently slow enough that this kind of
thing can be caught before causing serious damage. As more naive users
(or equally naive `sysadmins') get access to fast connections, the
possibility of someone being sued for (literally) millions of dollars
(pounds, francs, ...) because they screwed up their mail configuration
could easily become a reality.
-- Glynn Clements <glynn@sensei.co.uk> - To unsubscribe from this list: send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.rutgers.edu