User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020605 Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020605 Spamassassin (http://www.spamassassin.org) is a Perl module that detects spam and allows users to route it rather than being forced to read it. One of its useful features is that it strips MIME and converts the entire document to text, so that web bugs (images with long user identification strings, etc.) are rendered useless. Mozilla somehow refangs the mail (rebuilds the document assuming all the MIME types at the document's separators are correct) without checking the overall document type. Reproducible: Always Steps to Reproduce: 1. First, install SpamAssassin. 2. Next, give a spammer your e-mail address and wait for some multipart MIME/HTML spam to appear in your inbox. This shouldn't take long :-). 3. Hopefully, SpamAssassin will have tagged the message so you can use one of Moz's mail filters to kick it into its own folder. The message should be "defanged" -- converted globally to HTML type text/plain in the headers. 4. Try to forward the defanged message. Actual Results: You'll see rendered HTML. Expected Results: The same defanged message. Since you guys probably don't have SpamAssassin running around your network, I'll attach an example in a followup.

Alternatively, you could just mail yourself the attachment above and forward it to verify the bug.

This is not a Mozilla issue, but a SpamAssassin issue. It was resolved starting in 2.50. The messages from then on are attached.

marking fixed per comment 3.

Nothing in Mozilla was broken or fixed.

->WORKSFORME

Okay, I'm reopening this. The problem is that attachments aren't treated as attachments but are rendered anyway. This is Bad if you're trying to avoid detection as a Real Human Being thanks to web bugs and other nasties that rely on HTML parsing/processing.

Changing the summary to more accurately reflect the problem.

You will run smack into this problem whenever someone sends you a bunch of large digital camera images. Mailnews and/or thunderbird insists on downloading and displaying each and every one of them from the IMAP server. Content-disposition-tags notwithstanding. I got a 12MB batch of images today and mozilla had not been able to open the message in 20 minutes using the company 10Mbps net access. Needless to say, using the mailserver web frontend, downloading those images tooks less than a minute.

comment 9 is bug 147461

Jo Hermans is right about the duplicate. *** This bug has been marked as a duplicate of 147461 ***