User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.0 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.1) Gecko/20060130 SeaMonkey/1.0 If in a mail message a long header line is wrapped onto multiple actual lines, the mail filters won't "see" anything past the first actual line. It seems that mail filtering is doing a raw line-by-line search instead of properly reading the mail headers, parsing multiple actual lines as one long logical line, and only then looking at the contents of that reassembled long line. Reproducible: Always Steps to Reproduce: 1. Get a message message to the dev-tech-crypto.lists.mozilla.org list, whose messages wrap the List-Id header onto multiple lines: List-Id: "discussion of mozilla's crypto code &amp; features" <dev-tech-crypto.lists.mozilla.org> 2. Create a filter that checks whether the List-Id field contains the string "dev-tech-crypto.lists.mozilla.org" (and, of course, that performs some action you can detect). Run the filter on the message and notice that the filter does _not_ operate on the message. 3. Change the filter to check for "discussion of mozilla". Run the filter on the message again and notice that now the filter _does_ operate on the message. Actual Results: See above. Expected Results: The filter should have selected the message in both cases (regardless of whether the header field value was broken onto multiple lines or not).

*** This bug has been marked as a duplicate of 124641 ***