Can't find link to email Yahoo directly. I keep getting a popup every time I go to my Inbox from Dasi Hatano?

Every time I go into my Inbox of Yahoo email a popup box comes up the last few days from Hasi Datano. How can someone put that in my Email box to pester me. I've clicked the X at top and it goes away but is back next time. I don't want to click the acccept or decline as it may be a virus trying to get in. Either way it should not be permitted to enter a person's email boxes. I've tried to get hold of Yahoo but only get scripted boxes to check off which do not match the problem. Got hold of someone on Yahoo Messenger but he couldn't help. BTW at the bottom of this popup it says Y Messenger. Any help thanks.