I was just doing a little test, it turns out a lot of IP addresses from Telkom, which is still blocked by Spamhaus.org because of spam.
There are three kinds of IP blocking, that are through the SBL, XBL and PBL. If your IP is blocked and can not send mail using mail client such Outlook Express to several servers, you can remove your blocked IPs at the Blocklist Removal Center: http://www.spamhaus.org/lookup.lasso
