This question already has an answer here:
Recently I have setup a mail server with
Squirrelmail on Ubuntu cloud server. The server has static ip address with proper MX record(mail.mydomain.net). When I send mail to Google its going to Spam and I should mark as not spam and yahoo is not at all receiving. Is there anything apart from Static ip and MX record to validate my domain name so that all external domains receive mails sent from my mail server without any problem?. Please need help...