you can follow these steps to debug the issue:

1. Verify Outgoing Server Configuration: Double-check the configuration of your outgoing server in Odoo. Make sure the server settings (SMTP server, port, username, password, etc.) are accurate and correspond to a functional email server.

2. Check Email Templates: Ensure that the email templates related to the Auth Signup process are properly configured. You can navigate to "Settings" > "Technical" > "Email" > "Templates" in Odoo and search for templates related to user signup or authentication. Verify that the templates contain the correct content and placeholders for dynamic information.

3. Verify Email Delivery Method: Odoo provides different email delivery methods. Make sure you have the correct method configured. In Odoo 13.0, you can check this by going to "Settings" > "General Settings" > "Email" > "Outgoing Mail Servers" and ensuring that the "SMTP Server" is selected as the delivery method.

4. Check Email Server Logs: Access the logs of your email server to see if there are any errors or issues reported during the time of signup attempts. Look for any error messages that might indicate the reason for the email not being sent.

5. Review Odoo Server Logs: Check the Odoo server logs for any related error messages or warnings. The logs can provide insights into potential issues with the email sending process. You can find the server logs in the Odoo server's log file, usually located in the "var/log" directory.

6. Test Email Sending: You can test the email sending functionality by manually triggering an email from Odoo. Go to "Settings" > "Technical" > "Email" > "Templates", select the template you want to test, and click on the "Preview & Send" button. Verify if the email is sent successfully or if any error messages are displayed.

7. Firewall and Security Settings: Ensure that the firewall or security settings on your server or network are not blocking the outgoing email traffic. Check if the SMTP port you are using is open and accessible.

Hi

Could you please check how you set up the outgoing mail, Please check how to set up the email values, especially the 'email_to', maybe you have to assign the email_to as user.partner_id.email so could you check if the corresponding partner has any user otherwise please change the email_to values.