Mail sending problem using php 7.0

Hi… as per mentioned in this link to check php is sending mail or not ( I am using ubuntu 16.04 so i tried that command as mentioned php -a and after that mail (‘mail id’, “Test Postfix”, “Test mail from postfix”);. i am not getting any error msg there in console but when I check my log.mail file it says me (Helo command re$ and rejected: need fully-qualified hostname (in reply to RCPT TO command))) even m not getting any mail so could you please help me regarding so that i can fix my problem …thnks

Try setting up FQDN in /etc/hosts file. Setup is it something like below: localhost


this is my domain can you mention how to add…