[Pkg-exim4-users] batv and sender verification

[Marc Haber]

On Mon, Feb 04, 2008 at 04:26:10PM +0200, Johann Spies wrote:
> pkg-exim4-users at lists.alioth.debian.org
> SMTP error from remote mail server after RCPT TO:<pkg-exim4-users at lists.alioth.debian.org>:
> host lists.alioth.debian.org [217.196.43.134]:
> 550-Verification failed for <prvs=jspies/092037e01f at sun.ac.za>
> 550-Called:   146.232.64.13
> 550-Sent:     RCPT TO:<prvs=jspies/092037e01f at sun.ac.za>
> 550-Response: 550 restricted characters in address
> 550 Sender callout failed: Sender adress can't be verified trough SMTP check.

  # The following section of the ACL is concerned with local parts that contain
  # certain non-alphanumeric characters. Dots in unusual places are
  # handled by this ACL as well.
  #
  # Non-alphanumeric characters other than dots are rarely found in genuine
  # local parts, but are often tried by people looking to circumvent
  # relaying restrictions. Therefore, although they are valid in local
  # parts, these rules disallow certain non-alphanumeric characters, as
  # a precaution.
  #
  # Empty components (two dots in a row) are not valid in RFC 2822, but Exim
  # allows them because they have been encountered. (Consider local parts
  # constructed as "firstinitial.secondinitial.familyname" when applied to
  # a name without a second initial.) However, a local part starting
  # with a dot or containing /../ can cause trouble if it is used as part of a
  # file name (e.g. for a mailing list). This is also true for local parts that
  # contain slashes. A pipe symbol can also be troublesome if the local part is
  # incorporated unthinkingly into a shell command line.
  #
  # These ACL components will block recipient addresses that are valid
  # from an RFC2822 point of view. We chose to have them blocked by
  # default for security reasons.
  #
  # If you feel that your site should have less strict recipient
  # checking, please feel free to change the default values of the macros
  # defined in main/01_exim4-config_listmacrosdefs or override them from a
  # local configuration file.
  #
  # Two different rules are used. The first one has a quite strict
  # default, and is applied to messages that are addressed to one of the
  # local domains handled by this host.

  # The default value of CHECK_RCPT_LOCAL_LOCALPARTS is defined in
  # main/01_exim4-config_listmacrosdefs:
  # CHECK_RCPT_LOCAL_LOCALPARTS = ^[.] : ^.*[@%!/|`#&?]
  # This blocks local parts that begin with a dot or contain a quite
  # broad range of non-alphanumeric characters.
  .ifdef CHECK_RCPT_LOCAL_LOCALPARTS
  deny
    domains = +local_domains
    local_parts = CHECK_RCPT_LOCAL_LOCALPARTS
    message = restricted characters in address
  .endif

  # The second rule applies to all other domains, and its default is
  # considerably less strict.

  # The default value of CHECK_RCPT_REMOTE_LOCALPARTS is defined in
  # main/01_exim4-config_listmacrosdefs:
  # CHECK_RCPT_REMOTE_LOCALPARTS = ^[./|] : ^.*[@%!`#&?] : ^.*/\\.\\./

  # It allows local users to send outgoing messages to sites
  # that use slashes and vertical bars in their local parts. It blocks
  # local parts that begin with a dot, slash, or vertical bar, but allows
  # these characters within the local part. However, the sequence /../ is
  # barred. The use of some other non-alphanumeric characters is blocked.
  # Single quotes might probably be dangerous as well, but they're
  # allowed by the default regexps to avoid rejecting mails to Ireland.
  # The motivation here is to prevent local users (or local users' malware)
  # from mounting certain kinds of attack on remote sites.
  .ifdef CHECK_RCPT_REMOTE_LOCALPARTS
  deny
    domains = !+local_domains
    local_parts = CHECK_RCPT_REMOTE_LOCALPARTS
    message = restricted characters in address
  .endif

(this has been taken verbatim from Debian exim4's default
configuration).

If you have any more questions after reading this documentation,
please ask again.

Greetings
Marc

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