Comment 6 for bug 1475915

I agree with Mathias, this conceptually is the same as in return receipts in ordinary email; it is a feature implemented by Mail User Agents, and every (serious) Mail User Agent permits the user to disable it. If this feature is part of the Telegram protocol, the protocol itself is seriously broken, and in that case I will avoid at all Telegram usage.
MDNs (RFC 3798) are a formalization of "Return Receipts" for being processedby, but exactly for the same privacy reasons Mathias refers to, "requests for MDNs are entirely advisory in nature - i.e. recipients are free to ignore such requests": https://en.wikipedia.org/wiki/Return_receipt#Message_disposition_notifications