> Probably need SPF, SenderID, DomainKeys and DKIM setup to be safe.

As this is an outgoing mail server for an ISP, 1000's of domains's could come from it depending on how many email domains they host. Getting every domain to add SFP/SenderID records and DKIM records in the DNS and for the ISP to sign every email with a different DKIM keys etc would be virtually impossible.

The Standard Yahoo do have a "feedback loop" (and you have to have DKIM setup) but its based on a domain name so useless in getting an IP Address accepted.

So on : http://help.yahoo.com/kb/index?locale=en_AU&y=PROD_MAIL&page=content&id=SLN3327

It says to go to:

https://io.help.yahoo.com/contact/index?locale=en_US&y=PROD_MAIL&page=contact 

For IP Address feedback loop for ISPs. What options to choose.. I would just guess..