XF 1.1 email confirmation Problem

im a newbie here,. my new members cannot receive an email after they have registered, but facebook registration is ok, only the xenforo registration, they cannot receive any email from xenforo, how to fix this, pls help!
i check my spam folder in my google account and i found the confirmation but why on spam folder, is it possible to send it to inbox instead of spam folder? and also when i use my yahoo account for registration i cannot receive email from xenforo, only google but on spam folder