Q0906

Q0906

Question

How do I reject messages that don't have a Message-ID header? How do I fix MUAs that don't supply a Message-ID?.. qend

Answer

How to check for it

RFC2822 says a Message-ID header SHOULD be present. Sometimes the lack of a Message-ID is a spam indicator, so you might want to reject messages which don't have a message-ID.

In the ACL that runs when the message body is inspected near the top put:

# Check for the presence of a Message-Id: header, which RFC2822 says SHOULD be present.
# Some broken or misconfigured mailer software occasionally omits this from genuine  
# messages too, though -- although it's not hard for the offender to fix 
# after they receive a bounce because of it.
#
deny    condition  = ${if !def:h_Message-ID: {1}}
        message    = RFC2822 says that all mail SHOULD have a Message-ID header.\n\
                     Most messages without it are spam, so your mail has been rejected.

This may be named acl_check_data in which case you will have a line acl_smtp_data = acl_check_data near the top of the config file.

MUA/MTAs that have known problems

• jmail: here is a solution: http://www.dimac.net/support/Forum/topic.asp?TOPIC_ID=479&SearchTerms=Message-ID
• MS outlook 2003: the problem is fixed with SP2: http://www.smartertools.com/forums/p/10352/18717.aspx

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