[lug] Blocking SPAM and Viruses

[Jeffrey Siegal]

For blocking spam we use a multilayer approach of blocking some highly
abusive servers and domains at the mail server and using a procmail
filter (based on something free from the net called "junkfilter") to
insert a "probably spam" header into the messages against which users
can filter into a "probably spam" folder.  It isn't perfect but it cuts
down the number considerably.

For viruses, we strip out all attachments period (except a few
known-safe formats) going to users we can't trust not to open dangerous
attachments (pretty much everyone except me; I know better).  We block
outgoing mail from Outlook (based on the X-Mailer header) to make sure
that people don't use it.  (Everyone uses either Eudora, Netscape,
Mozilla, or one of the Linux text-mode mailers -- mutt, Mail, etc.)