https://bugs.exim.org/show_bug.cgi?id=1684
Bug ID: 1684 Summary: Malformed headers which exceed length spec willingly passed to remote servers Product: Exim Version: 4.80 Hardware: x86 OS: Linux Status: NEW Severity: bug Priority: medium Component: Transports Assignee: ni...@exim.org Reporter: ru...@afternet.org CC: exim-dev@exim.org The SMTP Spec states that: > 2.1.1. Line Length Limits > There are two limits that this standard places on the number of > characters in a line. Each line of characters MUST be no more than > 998 characters, and SHOULD be no more than 78 characters, excluding > the CRLF. However, if exim gets a message in the queue whose line length is longer than 998 chars it will happily send it to other hosts, thus violating the protocol. In addition, MANY MTAs (including gmail) will respond to an over-length line by hanging up on the connection (TCP RST) without any error message. Exim misclassifies this as a host error (as documented in http://www.exim.org/exim-html-current/doc/html/spec_html/ch-smtp_processing.html#SECToutSMTPerr) As a result, sending messages that contain long header lines to a local server for delivery to a remote site can interrupt delivery of legitimate messages to that remote site. This has been seen with certain "References" headers. -- You are receiving this mail because: You are on the CC list for the bug. -- ## List details at https://lists.exim.org/mailman/listinfo/exim-dev Exim details at http://www.exim.org/ ##