Please provide a snippet of the part of the specification which we violate
.. Although the recipient's server SHOULD discard a delayed delivery notation whose 'from' attribute matches the server's JabberID (or return a <not-acceptable/> error to the originator)..
Please provide a link to the specification:
As a client developer i want to trust a server added delay and distrust a client added delay.
If the "from" is not sanitized, it means i have to distrust all delays, which means i have to show offline messages received in the same way as when a user sends a delayed message.