Individual clients can change their settings by logging into their email and going to the Mail->Spam menu.

We both publish and honor SPF records (http://spf.pobox.com/).

If a message's header's date is < or > 2005 it is rejected. Spammers use this to make messages appear at the top or bottom of a date sorted inbox. If it is a valid message, the sender needs to set their system clock to the correct date and time.

If a virus is found in the message, it is silently dropped. The return path address is probably forged, so sending a notice does not help. The client can bypass this if they want (Why???).

If the message has malformed headers, it is bounced. Malformed headers are usually a sign that the message was sent using spamware. The client can bypass this if they want.

If the message has files with banned extensions attached, it is bounced. The sender can either rename or compress the file (zip, rar, etc.) and resend, or the client can disable the banned file check. This does however increase their risk of receiving viruses that our scanner does not yet catch.

The list of banned file extensions follows:

.ade
.adp
.b64
.bas
.bat
.bhx
.chm
.cmd
.com
.cpl
.crt
.dll
.exe
.hlp
.hqx
.hta
.inf
.ins
.isp
.js
.jse
.lnk
.mdb
.mde
.mim
.msc
.msi
.msp
.mst
.pcd
.pif
.reg
.scr
.sct
.shs
.shb
.uu
.uue
.vb
.vbe
.vbs
.wsc
.wsf
.wsh
.xxe

The following mime types are also banned:
application/x-msdownload
application/x-msdos-program
message/partial
message/external-body


The information at these URL's may help:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q262631 http://www.cknow.com/vtutor/vtextensions.htm

If a message is tagged as spam, it is bounced.
Scores > 4 have information added to the message header
Scores > 6.3 are tagged as spam and bounced.


Tagging is done with SpamAssassin (http://spamassassin.apache.org/)


The client can override these settings as well as a few others.

The control panel for these settings is in webmail under Mail->Spam.