How to open Port 25

Dear Friends,

I have installed Sentora on CentOS 7 (minimum install 64 bit).
I'm however unable to send emails while I can receive them.

It was working fine earlier and it stopped when tried to upgrade to CentOS 7.

Attached is the screenshot where it says, SMTP Port 25 is Closed.

I really appreciate your help in this regard.

Thanks in advance...

Best Regards,
FK

  smtp.jpg (Size: 61.28 KB / Downloads: 4)