«This email address is already assigned to another user» on `newsletter/subscriber/new`

[dmitrii-fediuk]

[
    IP Address: 172.71.222.157
    OpenMage: 19.5.2
    PHP: 7.4.33
    Post: [
        email: …
    ]
    Referer: https://www.thehcginstitute.com/store/checkout/onepage/success/
    Request Method: POST
    URL: https://www.thehcginstitute.com/store/newsletter/subscriber/new/
    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/127.0.0.0 Safari/537.36
]
EXCEPTION
This email address is already assigned to another user.
************************************
1   Mage::throwException
    app/code/core/Mage/Newsletter/controllers/SubscriberController.php:61

2   Mage_Newsletter_SubscriberController::newAction
    app/code/core/Mage/Core/Controller/Varien/Action.php:422

3   Mage_Core_Controller_Varien_Action::dispatch
    app/code/core/Mage/Core/Controller/Varien/Router/Standard.php:256

4   Mage_Core_Controller_Varien_Router_Standard::match
    app/code/core/Mage/Core/Controller/Varien/Front.php:182

5   Mage_Core_Controller_Varien_Front::dispatch
    app/code/core/Mage/Core/Model/App.php:365

6   Mage_Core_Model_App::run
    app/Mage.php:742

7   Mage::run
    index.php:62

1   Mage::throwException
    app/Mage.php:654

2   Mage_Newsletter_SubscriberController::newAction
    app/code/core/Mage/Newsletter/controllers/SubscriberController.php:61

3   Mage_Core_Controller_Varien_Action::dispatch
    app/code/core/Mage/Core/Controller/Varien/Action.php:422

4   Mage_Core_Controller_Varien_Router_Standard::match
    app/code/core/Mage/Core/Controller/Varien/Router/Standard.php:256

5   Mage_Core_Controller_Varien_Front::dispatch
    app/code/core/Mage/Core/Controller/Varien/Front.php:182

6   Mage_Core_Model_App::run
    app/code/core/Mage/Core/Model/App.php:365

7   Mage::run
    app/Mage.php:742