Hi,
thanks for the hint! I'm not using the exim-config stuff because it is a
mess to me. I copied over the example config that comes along with the
docs and started from there --- much easier than fumbling with
exim-config, and this way, I actually know what I have configured and
what not :) Also, it made (and still makes) me learn about the
differences between exim3 and exim4.
Checking the headers might reject legitimate mail, but since cyrus
doesn't deliver it anyway and sends out a delivery error message, it is
something that could be abused by SPAMers.
I had syntax checking on the headers enabled with exim3 before and was
missing it in exim4, but I didn't look into it until now that I'm seeing
mail rejected due to bad headers. Nobody complained about it in the last
three years :)
The following makes cyrus happy now:
acl_check_data:
# deny messages with invalid headers
deny message = Messages with invalid headers are not allowed.
log_message = invalid headers in message
!verify = header_syntax
# deny message if there are NUL characters in the message body
deny message = NUL characters in the message body are not allowed.
log_message =
NUL_chars%$tod_log%<$return_path>%<$recipients>%($body_zerocount)
condition = ${if > {$body_zerocount}{0} }
[...]
Denying NUL characters may also reject legitimate mail, but I didn't
like the ressource usage that might be involved with filtering all the
mail for it.
GH
Marc Haber wrote:
On Wed, 05 Apr 2006 13:57:59 +0200, listrcv <[EMAIL PROTECTED]>
in exim3, there was an option to check the syntax of mail headers
(headers_check_syntax or so).
How do I enable that with exim4?
Cyrus complains about invalid headers, so I want to check them before
such mail is handed over to cyrus. Messages with invalid headers should
be rejected before accepting them for not to have a possible exploit for
SPAMers.
If you are on Debian, you only need to set the macro
CHECK_DATA_VERIFY_HEADER_SYNTAX. The code is already there in the DATA
acl.
The default is off since this might reject legitimate e-mail.
Greetings
Marc
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