Hi, Yacob 

If the same email credentials for SMTP are working on other sites - then it is probably not wrong credentials, but rather something blocking the emails from WordPress.

An issue with email notifications could be caused by several reasons:

1. Your hosting provider is blocking all 3rd party settings and only allowing their SMTP (or other) settings.
2. Your website has a PHP version of less than 7.
3. The credentials are not correct.
4. There's something else blocking the notifications from being sent.
5. If you're using Gmail, please check out this article for detailed setup instructions.

Please check these points, and let me know if you were able to resolve the issue. If you're still not able to resolve the issue, we'll need to remote into your website, and see what's going on.

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If the issue persists - can do a test Email for you.

Please provide me a temporary WP-admin (administrator) user for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. 

We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course, we do not provide login data to third parties. 

You can write credentials here just check PRIVATE Reply so nobody can see them except us.

Hi, Yacob 

You can send me credentials here, just mark the message as Private, on the bottom right side > and only i wil see them. Send me a link to WP-Admin and the credentials, please, and i can test my credentials on your site. Thanks