There is an old thread called "Reply to message from meeting invite gets rejected"

There was never a conclusion. We are having the same issue with Exchange 2016 on premise an Outlook 2016. If someone accepts/declines/tentatives a meeting request, it generates an email to the meeting organizer. They might include some text like "can't make it" or something. While that might seem enough, if the meeting organizer then RESPONDS to the response, under certain circumstances the message will bounce. In Exchange it creates MSExchangeTransport 9216, MSExchange Extensibility 1051, and MSExchange Messaging Policies 4007.
Related to corruption and crc issue. The 1051 "Agent 'Transport Rule Agent' caused an unhandled exception 'TextConvertersException: CRC does not match, data corrupted' while handling event 'OnResolvedMessage'"
The 4007 is pretty long but the key is here. "TextConvertersException Error: Microsoft.Exchange.Data.TextConverters.TextConvertersException: CRC does not match, data corrupted"

I have tested this with multiple scenarios and what I can get to trigger it is if when the meeting Organizer includes their signature block (which contains graphics) in their response, it bounces. Also if you go into their Sent Items, the message is bloated, about 123K, and you cannot open it. I know, tell the users to not include their very pretty signature block when replying will cure that, but that is not going to fly.