Does anyone know how to reject pictures using postfix. there is a
spammer who is
displaying a picture with a paragraph and the body_checks cannot read
the words.
Thanks

On 26 Apr 2006 11:03:01 -0700, rogv24@yahoo.com wrote:

>Does anyone know how to reject pictures using postfix. there is a
>spammer who is
>displaying a picture with a paragraph and the body_checks cannot read
>the words.

I'm just a novice, so an expert may have a better idea.. But an
attachment is simply text your e-mail client converts to an
attachment. You could use a body check with something like "MIME", but
perhaps a better idea is to see perhaps what ISP that spammer is
connecting from and do some IP based blocking.

rogv24@yahoo.com wrote:
> Does anyone know how to reject pictures using postfix. there is a
> spammer who is
> displaying a picture with a paragraph and the body_checks cannot read
> the words.
> Thanks

In order to read text that's in an image file, the file needs to passed
through an optical character recognition (OCR) program.

This form of image/text spamming is heavily used by the stock market spammers, and
sometimes viagra spammers.

There was a discusison recently on the official Postfix mailing list about
the use of OCR and Postfix. While there are some free public domain OCR program
available, they just aren't very good yet. The ones I tried didn't do a good job at all in
character recognition. And, any deviation by the spammer, such as tilting the
characters and such, completely fooled the software.

You can completely block all image files based on their naming suffixes, but
this makes for some very unhappy users in today's world of image exchange.
--
Greg

Thats exactly whats happening here there is a bunch of stock market
spammers
and they have GIF pictures in the body of the email.
How would I reject these using the naming suffixes?
Thankyou

How are you presently handling these spams?

rogv24@yahoo.com wrote:
> Thats exactly whats happening here there is a bunch of stock market
> spammers
> and they have GIF pictures in the body of the email.
> How would I reject these using the naming suffixes?
> Thankyou
>

Here's an example that was found online, on how to block
executable attachments, but yet allows ZIP files. It could easily be modified to include
gif, gif, bmp, and etc.. images.

Note that this blocks in both directions. That means you can't send
any of these types of files either, without some add'l work to Postfix.
--
Greg



/etc/postfix/main.cf:
mime_header_checks regexp:/etc/postfix/mime_header_checks.regexp


/etc/postfix/mime_header_checks.regexp:
/^begin \d\d\d (.*\.(vbe|vbs|exe|com|cmd|dll|jb|bat|pif|scr|lnk))/ REJECT Our apologies, message content "$1" rejected: we do not accept certain attachments. You may use ZIP.

/^Content-(Disposition|Type)\:.*name="?(.*\.(vbe|vbs|exe|com |cmd|dll|jb|bat|pif|scr|lnk))"?/ REJECT Our apologies, message content "$2" rejected: we do not accept certain attachments. You may use ZIP.

/^\s*(file)?name="?(.*\.(vbe|vbs|exe|com|cmd|dll|jb |bat|pif|scr|lnk))"?/ REJECT Our apologies, message content "$2" rejected: we do not accept certain attachments. You may use ZIP.

rogv24@yahoo.com wrote:
> How are you presently handling these spams? {image spams}

I'm not in a position where I can block attachments; I require them.

So until something better comes along, I just try to rely on RBL
services. The chances are fair that the spam relay site's IP has already been
reported to some RBL site based on them spamming someone else.

No matter what you do, some spams are still going to get through.

--
Greg