For quite a while now Yahoo has been temporarily rejecting connections from my mail servers ‘due to user complaints’.
I joined their Abuse Feedback Loop program so I would be informed of these user complaints.
Unfortunately, the feedback loop isn’t working that well … as my server’s connections are still being deferred, but I’m not getting a lot of complaint feedback. Yahoo hasn’t returned any of my emails regarding it.
You can read more about the issue on my personal blog: http://www.geekyramblings.org/2009/08/25/yahoo-complaint-feedback-loop-redux/
As it is now, mail sent to Yahoo hosted email accounts will probably be rather significantly delayed (at least hours).
I don’t to have any similar problems with Gmail, Hotmail, or Comcast.
If you have any further questions about this, feel free to contact me directly.