On 2008-02-09 at 09:20 -0600, Craig Jackson wrote:
> Second, the problem with this mime acl: I understand something more
> since I went back and reread the spec.txt. The mime_filename is derived
> from the content_type or content_disposition headers - but no other. Not
> all MUAs set the filename in these headers. In the above case,
> mime_filename was set in the content_id header, thus Exim set
> mime_filename to the empty string. So why didn't Exim set the second
> part of OR condition (that is the content_type check) to true and thus
> the entire condition to true. I used exim -d+acl+expand -bh IPADDRESS to
> see all this. The answer must be that I made a mistake in there
> somewhere. So am rechecking and will get back to you. Thanks for your
> patience.
*sigh* Apparently, yesterday was not my day for reading comprehension.
Somehow I missed that the second example was one which was caught by the
filters and was provided as contrast to the first one. Sorry.
Right, Content-ID is not supposed to be used for specifying a filename
for saving a message or any such thing -- it's strictly for identifying
the sub-parts of a message so that things like HTML mail can refer to
those images for inline display.
See: RFC 2392 Content-ID and Message-ID Uniform Resource Locators
That RFC contains examples, etc; note that the fact that the value of
the header looks like a filename is an implementation detail of the
sender. If any software is sending this mail with the expectation that
those images be saved, it's broken. I suspect that you're just seeing
large background images in spam and discovering a hard limitation of
$mime_filename for spam-detection.
The content_type check is failing because when I said that it would work
accidentally I was wrong; yesterday really was an off day for me.
You're requiring that the content-type _start_ 'bmp' or the like, using
an anchored regexp. A content-type is formed type/subtype so since you
don't allow for the image/ or application/ part, you'll never match
there.
-Phil
PS: I read private email via my machine in Europe. Exim was developed
by a British developer and the primary maintainers are all in the
UK; ghettoisation will bite you hard.
