Spam Filtering and Common Carrier Status
The Ferris Research blog has an entry on ISPs and whether spam blocking is at odds with the common carrier status that seems to protect them from certain liabilities:
This debate is happening again. Thanks to the good work done by MAAWG and others, ISPs are being encouraged to set up outbound spam filtering, to prevent virus-infected PCs sending spam from their networks and to encourage users to clean their infected machines by use of a walled garden. Naturally, some are expressing concern that such discrimination would count as another chink in their common carrier armor.
It’s time for the FCC and similar regulators in other countries to step up and make it clear that such genuinely useful — some would say essential — discrimination would not affect an ISP’s common carrier status.
I personally don’t think that ISPs should risk their common carrier status for filtering mail, but not because spam filtering is useful, instead because such filtering does not occur at the network level.
Let’s say a spam message enters the network of my ISP: the ISP does not block the packets containing the spam message at the edge of the network, instead the spam message is delivered without discrimination to the ISP’s mail server. The ISP’s mail server then filters the message and if the message is not spam the ISP will later deliver the message to my mail client across their network, again without discrimination.
It is the ISP’s network that acts as a carrier, not their mail servers. Even on the outbound side, it would be ISPs filtering mail entering their mail servers from inside the network for external delivery. In every case the network itself would just be carrying packets containing the messages to the appropriate mail servers.
