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5 messages in net.sourceforge.lists.courier-usersRe: [courier-users] 8-bit MIME charac...| From | Sent On | Attachments |
|---|---|---|
| Michael Heß | Jan 23, 2001 12:20 am | |
| Alexei Batyr' | Jan 23, 2001 1:30 am | |
| Michael Heß | Jan 23, 2001 2:35 am | |
| Patrick Price | Jan 23, 2001 3:26 am | |
| Daniel Biddle | Jan 23, 2001 3:56 am |
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| Subject: | Re: [courier-users] 8-bit MIME characters in mails ... | Actions... |
|---|---|---|
| From: | Daniel Biddle (del...@osian.net) | |
| Date: | Jan 23, 2001 3:56:18 am | |
| List: | net.sourceforge.lists.courier-users | |
On Tue, 23 Jan 2001, Michael Heß wrote:
Hi there!
I´m experiencing some strange behaviour over here. I just got a mail from a friend, which was delivered correctly to my sendmail based POP3 account, but was rejected by the esmtp/courier combo. The following is a copy of the reject-mail
Reporting-MTA: dns; gw.ordix.de Received-From-MTA: DNS; mailix.ordix.de Arrival-Date: Tue, 23 Jan 2001 09:05:11 +0100
Final-Recipient: RFC822; mh...@chunk.ordix.de Action: failed Status: 5.2.0 Remote-MTA: DNS; chunk.ordix.de Diagnostic-Code: SMTP; 550-The headers in this message contain 8-bit text, which violates RFC 2047. Last-Attempt-Date: Tue, 23 Jan 2001 09:05:12 +0100
Is this a problem of ESMTP (maybe it can´t handle it?) and I have to switch to QMail, or is there anything I might have missed while configuring, which causes the problem?
RFC 2047 defines a way of encoding non-ASCII characters such as the ß in your name into ASCII which can be safely transmitted through various broken mail systems. For instance, here's how your name and address were recorded in the messages I received from you:
From: =?iso-8859-1?Q?Michael_He=DF?= <mh...@ordix.de>
This labels the non-ASCII character in your name as being from ISO 8859-1 (Latin1), which lets my mail client correctly decode this as "Michael Heß" when displaying your name. If I sent a message directly to you, it would encode it in the same way.
However, it seems your friend's mail program did not correctly encode or label the non-ASCII characters in the header (probably including your name), but sent them through unlabeled, making it impossible for the receiving software (in this case Courier) to exactly identify the characters.
Sendmail didn't bother to check for this error, and since your friend presumably also uses ISO 8859-1, neither of you noticed any strange characters.
Courier however is much fussier about what it will accept. It refuses to pass on messages that are not entirely correct, so that (in theory) the sender is forced to fix their system to send only correct mail. (This is somewhat like refusing to talk to someone who mispronounces your name.)
You have two possibilities for what to do now:
1) Tell your friend to change his/her mail system to send mail headers encoded according to MIME (RFC 2047) in 7 bits, instead of unlabeled in 8 bits;
2) Modify Courier to ignore this error in the headers, and deliver the mail anyway. Note that:
a) your friend's mail system won't be fixed, and so will continue to send out mail with headers containing characters that will be misinterpreted by some recipients;
b) some mail you receive will have characters misinterpreted in the headers;
c) Courier's author won't help with this;
d) there may be other problems as Courier will be working in a way it wasn't designed to.
If you decide to do this, the message quoted below should be of some use.
Hope this helps!
-- Daniel Biddle <del...@osian.net>
PS. Please note that ' is the apostrophe, as used in "I'm" and "can't". ´ is a spacing acute accent, and should not appear in normal text. Thanks.
On Tue, 23 Jan 2001, Michael Heß wrote:
Thanks for the info, but I´m afraid I can´t view this message. I´m rather new to this list (I subscribed last Friday), and the archives end at dec, 15, 2000. Is there another archive than the one at http://lists.sourceforge.net/lists/listinfo/courier-users, or can you send this thread to me via email ?
Thanks in advance, Michael
The relevant section is:
2047
550-The headers in this message contain 8-bit text, which violates RFC 2047. Sorry, I cannot accept any mail without the required MIME headers. See <URL:ftp://ftp.isi.edu/in-notes/rfc2047.txt> for more information.
Solution:
You can try modifying the function SubmitFile::MessageEnd() in courier/submit2.C, and remove the code that reports both 8-bit related errors, RFC2045_ERR8BITHEADER and RFC2045_ERR8BITCONTENT. This will suppress the error and accept the mail, but I can't really evaluate what the full consequences are. Do not remove the code that reports RFC2045_ERR2COMPLEX, this error indicates a denial-of-service attack.
-- Daniel Biddle <del...@osian.net>