When I send emails, I sometimes receive an email from "Content-filter at mail.s2ki.com" with the subject "Delivery status notification, invalid header section: all-whitespace header line".

Inside the e-mail, this is what I see...

Your message WAS SUCCESSFULLY RELAYED to:
<destination_email>

This delivery report was generated by the program amavisd-new at host
mail.s2ki.com. Our internal reference code for your message is
06160-08/BCukbTnuIxHy

INVALID HEADER: FOLDED HEADER FIELD LINE MADE UP ENTIRELY OF WHITESPACE

Improper folded header field made up entirely of whitespace: References:
...6.squirrel@www.s2ki.com>\n \n <B4A34D55F[...]

Return-Path: <my_email>
From: "My Name" <my_email>
Message-ID: <ip_address.squirrel@www.s2ki.com>
User-Agent: SquirrelMail/1.5.1
Subject: <my_subject>

IMPROPERLY FOLDED HEADER FIELD LINE MADE UP ENTIRELY OF WHITESPACE

The RFC 5322 document specifies rules for forming internet messages.
In section '3.2.2. Folding white space and comments' it explicitly
prohibits folding of header fields in such a way that any line of a
folded header field is made up entirely of white-space characters
(control characters SP and HTAB) and nothing else.

Can this problem be fixed? Thanks.

 

It's not a problem. Your email was delivered. It's a warning message and I think it has to do with address book issues in webmail. Check your address book entries for the email addresses you are having the problem with. It only happens when sending to specific addresses.

 

As long as the email was delivered, I guess it's fine. Just that the auto-response messages get annoying. The destination email addresses were not used from the address book and some of those auto-messages were generated from simply replying to people. Yea, it does only happen to specific people, but again, not used from address book. Also, 2 days ago, I never received those auto-messages, just started happening recently. Thanks.