An update for the y!groups mailer list March 8, 2007:
current complete list as of Dec 5, 2006:
Adding these addresses to your whitelist helps ensure that client
email is not blocked due to false positives from filters.
For more information about how to read these address ranges,
In short, an address block like 184.108.40.206/24 means
all the addresses from 220.127.116.11 through 18.104.22.168
should be allowed to send mail as these are Yahoo! Groups
outbound mail servers.