UPDATE 20th December 2010:
Mails sent to yahoo are getting delayed upto 4hours.
Lately we noticed that there is a problem delivering Email activation to Yahoo users. We are looking into the issue and talking to Yahoo regarding the same. We should be able to sort out the issue soon. Members who are facing activation issues please post here and we would try to sort the issue individually.
However I would personally suggest my friends to move to Gmail which is far better then Yahoo Mail whose service has really gone down.
Regards,
Vijay