Telegram adds content to 'sent history' without user's consent

[Rüdiger Kupper]

THIS IS A SEVERE PRIVACY ISSUE!
The Telegram service has several times changed the content of my messages, without my consent.

I have recently sent some messages to other Telegram users containing links to Amazon web pages or other commecial web pages. My intent was to ask my friends about their opinion about the respective product.

TELEGRAM HAS REPEATEDLY AND WITHOUT MY CONSENT CHANGED THE CONTENT OF THESE MESSAGES, adding very obviously commercial content!

As an example:

The message I have sent via Telegram read the follwowing:
--------- snip: Original Telegram message --------------
Mit Punkten oder ganz gelb?
http://blackroll.de/collections/blackroll/products/blackroll-mini
--------------------------------------------------------

The message ended here, without any other content.

The message my peer recieved was:
------------ snip: Message as modified by Telegram -----
Mit Punkten oder ganz gelb?
http://blackroll.de/collections/blackroll/products/blackroll-mini
> BLACKROLL.de
> BLACKROLL (R) MINI by
> Blackroll | BLACKROLL.de
> Die BLACKROLL (R) MINI
> Faszienrolle:praktisch für unterwegs...
--------------------------------------------------------

This is clearly unauthorized content added to my message with commercial intent.
THIS BEHAVIOUR IS UNACCEPTABLE. YOU **MUST** STOP THE TELEGRAM COMPANY FROM CHANGING MESSAGE CONTENT!

If a security breach like that will occur again, I will immediately cancel my Telegram account and I will be warning all my peers from using it. Ubuntu Phone will then be left without a messaging app. I believe you do not want that to happen.

[Rüdiger Kupper (ruediger.kupper)]

Update:
My peer does report she did not receive the message as it shows up in my message history. She received the message I have originally sent. I must hence correct the subject of this ticket:
"Telegram adds content to 'sent history' without users consent."

[Rüdiger Kupper (ruediger.kupper)]

The modified content shows up only in my "message sent history", not in the messages received by my peers.
STILL, THIS IS UNAUTHORIZED MODIFICATION OF MY MESSAGES. THIS MUST BE STOPPED.

[Rüdiger Kupper (ruediger.kupper)]

This happens when sending messages that contain links to web pages. Telegram seems to query the linked page and adds content to my message sent history, making it look as if I had included that content.
The desktop version of telegram seems to be much more "creative" in this respect. But also the app adds contents, like images taken from the referenced page, to my history. this means, I cannot send a link via Telegram, without having Telegram query that link. I'm not sure if this is really a security issue, but it certainly is highly undesired behaviour.
It lowers my trust in Telegram: The messenger must not read the mail he delivers.