After trying to use the web archive to read the SPI mailing lists, I realise this is a very painful experience due to the amount of spam sent to the lists.
Please change the list configuration to only allow subscribers direct access to the lists, and send the rest of the postings for moderation.
If the moderation is done using the listadmin package (available in Debian Sarge/Sid), the script will take care of filtering out most spam (assuming spamassassin is used on incoming email), and the job of moderating the lists will only take a few seconds.
(I'm not talking about sensoring the list. I'm talking about rejecting spam and allowing real messages into the list.)