The term "backscatter" refers to non-delivery reports sent to a forged
return address. SMTP was created a long time ago, in better times where
everyone trusted each other. Anyone could use any return address on an
E-mail message. It's rather obvious how this can be a problem in modern
Backscatter becomes a problem when a mail server does not refuse to accept
unwanted mail. The mail server decides that the message is unwanted only
after it is accepted, and generates a non-delivery notice, which is sent to
the original message's return address. Viruses and junk mail use randomly
forged return addresses, so the victim of address forgery gets further
burdened with having to dig out massive amounts of useless non-delivery
notices from the mailbox.
This release of Courier adds several settings that help with stopping the
backscatter coming out of Courier.
=E2=80=A2 opt BOFHCHECKHELO=3D2 makes HELO rejections a temporary error code=
=E2=80=A2 Several new settings that control generation of backscatter bounce=
See new documentation in INSTALL. New command "courier clear address".
=E2=80=A2 With quotas enabled, a full maildir is now a temporary error, not =
permanent one. This configuration works better with backscatter filters.
=E2=80=A2 Documentation typos fixed. Minor error message tweaks.
=E2=80=A2 Open control files in append mode.