notification emil error

I have an embedded form on my website that adds people to my mailing list and tags them, thus trigerring an automation journey in MC. It works fine.

The problem is I want to get a notification email whenever a new sub is added, and checked the notification email option in MC4WP. that works fine on one of my domains, but the other produces an error even though I configured SPF and DKIM for thtat domain.

the full error bounced email text:

--------



This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

[email protected]
host gmail-smtp-in.l.google.com [74.125.71.26]
SMTP error from remote mail server after end of data:
550-5.7.26 Your email has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
550-5.7.26
550-5.7.26 Authentication results:
550-5.7.26 DKIM = did not pass
550-5.7.26 SPF [generationsnovels.com] with ip:
[5.154.240.65] = did not pass
550-5.7.26
550-5.7.26 For instructions on setting up authentication, go to
550 5.7.26 https://support.google.com/mail/answer/81126#authentication ffacd0b85a97d-37ee0bd7922si58469f8f.1072 - gsmtp
Reporting-MTA: dns; s-web09-us.upress.io

Action: failed
Final-Recipient: rfc822;[email protected]
Status: 5.0.0
Remote-MTA: dns; gmail-smtp-in.l.google.com
Diagnostic-Code: smtp; 550-5.7.26 Your email has been blocked because the sender is unauthenticated.
550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM.
550-5.7.26
550-5.7.26 Authentication results:
550-5.7.26 DKIM = did not pass
550-5.7.26 SPF [generationsnovels.com] with ip: [5.154.240.65] = did not pass
550-5.7.26
550-5.7.26 For instructions on setting up authentication, go to
550 5.7.26 https://support.google.com/mail/answer/81126#authentication ffacd0b85a97d-37ee0bd7922si58469f8f.1072 - gsmtp

Return-path: <[email protected]>
Received: from genec486 by s-web09-us.upress.io with local (Exim 4.98)
    (envelope-from <[email protected]>)
    id 1t2F5V-0000000EcDW-2Kso
    for [email protected];
    Sat, 19 Oct 2024 22:26:09 +0300
To: [email protected]
Subject: =?us-ascii?Q?New_bonus_story_download_on_Generationsnovels.c?= =?us-ascii?Q?om_:)?=
X-PHP-Originating-Script: 1080:PHPMailer.php
Date: Sat, 19 Oct 2024 19:26:09 +0000
From: WordPress <[email protected]>
Message-ID: <[email protected]>
X-Mailer: PHPMailer 6.9.1 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: text/html; charset=UTF-8

The page I need help with: [log in to see the link]