People keep adding me on Yahoo...?

Every morning when I log into Yahoo, I have 1-5 random people trying to add me...Today, one was "@yahoo.tw" (Taiwan?), and one was "@yahoo.it" (Italy?)...One was even "mohammed_boss_x5@hotmail.com" and had a lot of curly writing next to it (uming that's a personal message, and in Persian or something. Persian is the only curly writing I've every seen though)...I'm getting kindof worried here...What should I do/Am I safe?