I'm an open relay some how

[Stephen Atkins]

I've been administering the same postfix server for years so I'm a 
little confused as to how this happened.  Granted postifx hasn't been 
updated in a year or so.

This morning I came in to a mailq of over 93000 messages all destine to 
@yahoo.com.tw

For now I'm just blocking all email destined for this domain but I would 
really like to find out what happened.  I haven't changed my main.cf 
file for over a year.    I can post it if needed.

Thanks for the help.
--
Stephen Atkins