Undelivered Mail Returned to Sender

welcome
I have a problem on the server
The server receives messages without problems
But when I try to send the messages do not arrive and I get the following message

Undelivered Mail Returned to Sender
This is the mail system at host lathat-hala.

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

<xxx@gmail.com>: host gmail-smtp-in.l.google.com[172.217.222.27] said:
    550-5.7.26 This message does not have authentication information or fails
    to 550-5.7.26 pass authentication checks. To best protect our users from
    spam, the 550-5.7.26 message has been blocked. Please visit 550-5.7.26
    https://support.google.com/mail/answer/81126#authentication for more 550
    5.7.26 information. j23si3227741vso.295 - gsmtp (in reply to end of DATA
    command)
Reporting-MTA: dns; userxx
X-Postfix-Queue-ID: 53F88F0E67
X-Postfix-Sender: rfc822; info@domin.com
Arrival-Date: Mon, 25 Jan 2021 17:03:26 +0000 (UTC)

Final-Recipient: rfc822; xxx@gmail.com
Original-Recipient: rfc822;xxx@gmail.com
Action: failed
Status: 5.7.26
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 This message does not have authentication
    information or fails to 550-5.7.26 pass authentication checks. To best
    protect our users from spam, the 550-5.7.26 message has been blocked.
    Please visit 550-5.7.26
    https://support.google.com/mail/answer/81126#authentication for more 550
    5.7.26 information. j23si3227741vso.295 - gsmtp

Unable to read error messages, nor click on links contained within?
 

This is just what appears in the error message
Where can I find the error message?