Please i need help how do i know my messages are being deliverd

[maxwell33]

have been sending mails to companies emails but how i sure they recieved it yet ..

[Dmitry42]

When you compose new message in Roundcube you can with on something like: Delivery status notification.
But Recipient can choose "NO" in their mail-client program, when he ask "Send delivery status notification back to sender?".
So.. for 100% sure  - you can only call and ask him directly