Remove IPv6 from my plesk panel

My server CentOS Linux with Plesk panel I have a Plesk server and host some sites. Sometimes when an email is sent out there is a conflict with the not used IPv6 (2a01:4f8:10a:442f::2) I need to remove this IPv6 from my plesk server because I have no use for it. Email is sent out only from my IPv4 [login to view URL] Example error i get.... -----Original Message----- From: Mail Delivery System [mailto:MAILER-DAEMON@[login to view URL]] Sent: Thursday, May 16, 2019 8:45 PM To: george@[login to view URL] Subject: Undelivered Mail Returned to Sender This is the mail system at host eunet1.com. I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below. For further assistance, please send mail to postmaster. If you do so, please include this problem report. You can delete your own text from the attached returned message. The mail system <mdevicesagr@[login to view URL]>: host [login to view URL][2a00:1450:400c:c08::1b] said: 550-5.7.1 [2a01:4f8:10a:442f::2] Our system has detected that this message does 550-5.7.1 not meet IPv6 sending guidelines regarding PTR records and 550-5.7.1 authentication. Please review 550-5.7.1 [login to view URL] for more information 550 5.7.1 . h12si1022989wme.113 - gsmtp (in reply to end of DATA command)