Subject: Undelivered Mail Returned to Sender
From: [email-masked] (Mail Delivery System)
To: [email-masked]
Date: Mon, 25 Jan 2021 03:15:44 +0100 (CET)

This is the mail system at host cccp.at.

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

<[email-masked]> (expanded from <[email-masked]>): host
    aspmx.l.google.com[173.194.76.27] said: 550-5.7.26 Unauthenticated email
    from aol.com is not accepted due to domain's 550-5.7.26 DMARC policy.
    Please contact the administrator of aol.com domain if 550-5.7.26 this was a
    legitimate mail. Please visit 550-5.7.26
    https://support.google.com/mail/answer/2451690 to learn about the 550
    5.7.26 DMARC initiative. m12si13940591wml.162 - gsmtp (in reply to end of
    DATA command)