Spam mail problem?

I get this from mail delivery reports to a specific cpanel account: Event: failure Sender User: User1 Sender Domain: Domain1 From Address: agmailaccount@gmail.com Sender: User1 Sent Time: Jun 7, 2019, 2:00:14 PM Sender Host: Localhost Sender IP: 127.0.0.1 Authentication: localuser Spam Score: Recipient: amailruaccount@mail.ru Delivered To: Delivery User: -system- Delivery Domain: Router: dkim_lookuphost Transport: dkim_remote_smtp Out Time: Jun 7, 2019, 2:00:14 PM ID: 1hZCbf-00073K-I1 Delivery Host: mxs.mail.ru Delivery IP: 94.100.180.31 Size: 1.97 KB Result: ECDHE-RSA-AES256-GCM-SHA384:256 CV=yes: SMTP error from remote mail server after end of data: 550 spam message rejected. Please visit http://help.mail.ru/notspam-support/id?c=F5o_wmy5fwuAjKvBbqzLjEGkbinq4_1Gp7fQfJmTu7Y-La3rTpECD2T_hwgrCjQnZ-tn7yUBJZUwAAAAsRMAAHUaHyY~ or report details to abuse@corp.mail.ru. Error code: C23F9A170B7FB96CC1AB8C808CCBAC6E296EA44146FDE3EA7CD0B7A7B6BB9399EBAD2D3E0F02914E0887FF6427340A2BEF67EB6795250125. ID: 00000030000013B1261F1A75.
This mail was succesfully sent from my server and resulted as spam? How an email was send from a gmail account through my server?