@ginda
I too had your problem. I had to create an email address using the domain name email with my webspace/domain provider. example registration@mydomain.com. I then downloaded the plugin Stop WP Emails Going to Spam and installed it in wordpress plugins. I went to settings in my wordpress dashboard and found the plugin name. clicked it....under envelope sender Use Admin Email was selected by default but this was a gmail account for me. Using this as a redirect was keeping my emails out of the spam folder but still flagging it as possible spam. I then chose Use another Domain email. I typed in the email address I made associated with my domain name. This fixed everything. I then went to the email I had made with my domain name and told it to forward all the mail I get there to the email address I use all the time. You dont have to do this if you actually plan on using your domain name email.