Need help for our mail server

I send an email from Outlook and receive an error message. I can’t send an email to someone who was able to send it correctly yesterday.

Error message is as below:

More Info for Email Admins
Status code: 550 5.7.367

The sender’s message was routed to an email server outside Office 365 that returned an
error that it can’t relay the message. It’s likely that the server isn’t set up correctly to
receive and relay messages sent from challenergy.com or from javier.vidal.

The receiving server is not an Office 365 server - it’s likely one of your on-premises
servers in a hybrid environment, a server at a smart host email service that you’re trying
to route messages through, or possibly a server at an email hosting service you used in
the past (for example, when your MX record still points to your previous email service
provider). To fix this issue, try one or more of the following:

Check the error shown in the “Error Details” section below - Check the error to
determine what domain, service, or server is reporting the error. The email server needs
to be configured to either accept messages from anonymous users or to include the
sending domain or sending IP address in its list of authenticated senders. On an on-
premises Exchange server, you can set this up in the server’s receive connector. If it’s a
smart host managed by another service or partner, contact the service or partner and
ask them to configure their servers to accept and relay messages from your domain or
from your senders.

Make sure your MX/DNS records are correct - Work with your DNS hosting provider
(your domain registrar, Web hosting provider, or ISP) to make sure your MX records are
correctly set up to direct messages to the correct location.

Unfortunately, Office 365 support can’t help fix this problem because it’s likely due to
misconfigured settings on an email server outside Office 365.
Original Message Details
Created Date:
7/15/2021 1:30:07 AM
Sender Address:
{redacted}
Recipient Address:
{redacted}
Subject:
Re: 「見積依頼」歪ゲージ用の接着剤

Error Details
Reported error:
550 5.7.367 Remote server returned not permitted to relay → 554
5.7.1 <{redacted}>: Relay access denied
DSN generated by:
TY2PR01MB2603.jpnprd01.prod.outlook.com

If you pause cloudflare, does the issue persist?