W3C Mail

Unencoded 8bit characters in email headers

W3C's mail servers are configured to reject messages with unencoded 8bit characters in the message email headers.

If you tried to send email to W3C and received a bounce message directing you to this page, please contact your local postmaster, system administrators, or email software vendors to ask them to help you fix the problem.

Technical details:

RFC 2822 specifies rules for forming Internet messages. It does not allow the use of characters with codes above 127 to be used directly (non-encoded) in mail headers (it also prohibits NUL and bare CR).

If characters (e.g. with diacritics) from ISO Latin or other alphabets need to be included in headers, these characters need to be properly encoded according to RFC 2047. This encoding is often done transparently by mail readers (MUAs), but if automatic encoding is not available (e.g. by some older MUAs) it is the user's responsibility to avoid the use of such characters in mail headers, or to encode them manually. Typically the offending header fields in this category are 'Subject', 'Organization', and comment fields in e-mail addresses in the 'From', 'To' and 'Cc'.

Sometimes such invalid header fields are inserted automatically by some MUAs, MTAs, content checkers, or other mail handling services. If this is the case, that service should be fixed or properly configured. Typically the offending header fields in this category are 'Date', 'Received', 'X-Mailer', 'X-Priority', 'X-Scanned', etc.

(above text adapted from a bounce generated by amavisd-new)


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$Date: 2005/04/26 14:33:50 $