Email Problem

[indumetroindia]

I have successfully installed a Plesk on the digital ocean server, I am running a WordPress site buywindows10.org,

I am facing a problem in sending emails, WordPress not sending any emails also I have created webmail over the Plesk admin@buywindows10.org.

The email admin@buywindows10.org can receive emails but can't reply to the emails.

Even I am facing a database issue registered users are can't log in to the website.

 

[Dave W]

Check that Postfix is running,
Check the sites logs,
Check maillog, if your not happy using CLI use Mail-log

"facing a database issue registered users are can't log in to the website" may be a site issue, check logs, check firewall logs for the domain.

 

[Bitpalast]

but can't reply to the emails.

Can you describe what exactly happens when you click a "reply" button in your mail program and try to send the mail?
What is logged in /var/log/maillog (/var/log/mail.log) in that case?