James L. McGill <fishbowl(_at_)fotd(_dot_)netcomi(_dot_)com> wrote:
Does anybody have an explanation as to *why* they stick X-UIDL headers
in? And why haven't they stopped now that they've read this?
X-UIDL headers are added to messages by some POP servers when a client
retrieves the messages. This header field is used to help keep local maildrops
in sync with the server (it prevents duplicate copies of messages in a
maildrop).
The popular Qualcomm popper is one example of a server that inserts this header
field.
If a message retrieved from such a server is forwarded to another recipient, it
will most likely still have the X-UIDL header field in it, whether it is spam or
legitimate mail.
-Matt