Why can’t I just use the Outlook read confirmation?

Can I send „normal“ emails in addition to RMail?
4. Dezember 2017
What is the difference between a registered letter and a registered email?
4. Dezember 2017

Why can’t I just use the Outlook read confirmation?

Many users have disabled this feature. Furthermore, you cannot prove the content of your original message. Outlook confirmations („Delivered“ and „Read“) can be manipulated. The Registered Receipt of RMail cannot be manipulated and contains an encrypted version of the original content.