Ref: PBL114749 68.32.0.0/11 is listed on the Policy Block List (PBL) Outbound Email Policy of Comcast for this IP range: Email sent by Comcast subscribers using a mail program such as Outlook Express are required to send the email through Comcast. To insure your mail program is properly configured, please visit http://www.comcast.net/help/faq/index.jsp?faq=Email117481. If you are a Comcast Commercial Services customer and need support, please contact support_biz@cable.comcast.com
i used the sbl-xbl.spamhaus.org and now it works on my site.
Think I'll stay away from the pbl blocklist for checks such as this (and just use the PBL and XBL), as I suspect it wouldn't help much on a website anyway. Besides, blocking all Comcast subscribers would most definetely be a very bad idea as I understand they're quite big...right?