It looks like Yahoo has been getting itself banned by my mail server due to high levels of spam. I've enabled exceptions that detect Yahoo servers and exclude them from banning. I had something similar in place for AOL servers, but it seems that the method of detecting AOL servers was not always accurate. So, I've updated that to try and better detect AOL servers as well.
Anyway.. short version of this is that I have removed blocks that were in place on a number of Yahoo and AOL servers. For those of you having issues, I think it was primarily just Yahoo (inconsistently) and AOL.
Please try again, if you still have no been able to get your pictures successfully submitted and let me know if you hit more issues.
Thanks,
-Alex