WordPress is not sending emails

I am using gravity forms and contact form 7 and I dont know why but when I use my personal email with my domain, I dont get the mail. But when I change it to gmail account it magicly works.

Any ideas?

I have searched a bit and people said that they are having problems with gmail, so it have totaly confused me.

I have also tried to fix it using plugins but I am not sure about the configuration and the default didnt work.