I have the same problem. I see the emails in  'settings / technical / email' and they are marked as 'send', but nothing happens

hello, i do have the same problema, Odoo Online says: 

A default outgoing email server is already configured. You should not create an alternative one unless you really want to use a specific external outgoing email server for technical reasons.

but i cant send email, can you help ? 

Try this answer : https://www.odoo.com/nl_NL/forum/help-1/scheduled-action-email-queue-manager-does-not-send-automatically-email-from-queue-74396

You can go to settings / technical / email . you can have an idea why the emails arent sent .  

Hi,

If your Odoo version 16 is not sending emails as expected, even though it's stated that the SMTP server is already configured, there could be various reasons for this issue. Here are some troubleshooting steps you can follow to identify and resolve the problem:

1)Check Email Configuration:

Verify that your email settings within Odoo are correct. Go to the "Settings" module, select "Technical," and then "Email." Ensure that the SMTP server settings are accurate, including the server address, port, username, password, and security settings.

2)Test Email Configuration:

You can use the "Test" button within Odoo's email settings to verify if the email configuration is working correctly. This will send a test email to the specified email address. Ensure that this test email is delivered successfully.

3)Check Spam Folder:

Sometimes, emails sent from automated systems like Odoo may end up in the recipient's spam or junk folder. Check these folders to see if the emails are being delivered there.

4)Verify Email Addresses:

Ensure that the email addresses you are using in Odoo are correct. Incorrect email addresses can lead to delivery failures.

5)Firewall and Security:

Check if there are any firewall rules or security settings that might be blocking outgoing emails. Ensure that the SMTP server's IP address and port are not blocked.

6)SMTP Authentication:

Confirm that your SMTP server requires authentication (username and password) to send emails. If so, make sure the credentials are correctly configured in Odoo.

7)SSL/TLS Configuration:

If your SMTP server uses SSL/TLS encryption, ensure that the appropriate security settings are enabled in Odoo's email configuration.

8)SMTP Provider Issues:

Sometimes, the issue may not be with Odoo but with your email provider. Check with your email provider to see if there are any known issues or restrictions related to sending emails from applications like Odoo.
If you have gone through these steps and are still facing email delivery issues, it might be beneficial to reach out to your Odoo support or consult your system administrator for further assistance. They can help diagnose and resolve any server or configuration issues that might be affecting email delivery.

Hope it helps