Can someone help me please?

A delivery status notification or DSN usually is a report from one or more servers on what they did with your message. For example, your sending mail server may report that it successfully forwarded (relayed) the message. Some servers send them and some do not.

In 'Write' window: 'Options' > 'Delivery Status Notification' to request one. Most mail servers ignore it and you are more likely to get a DNS from your outgoing SMTP server that it handed the message onwards rather than the receiving server. So whether you get a response that it is useful is a hit and miss situation. I would not necessarilly rely on DSN.

'Options' > 'Return Receipt' A read receipt request is different, it triggers an action by the receiving mail software, assuming the administrator or recipient hasn't turned it off. Even if this gets through to the recipient they can choose to ignore it.

To combat spam issues, many servers are turning it off so spammers cannot use it to determine if they have a working address.

I believe this setting can force DSN to be sent. 'Menu icon' > 'Options' > 'Advanced' > 'General' tab click on 'Config Editor' button

In search type: mail.dsn look for this line:

• mail.dsn.always_request_on

When that is toggled true, the DSN request becomes permanent. Double click on line to toggle the value. Close Window click on 'OK'