Hi @Ardan Zaki,
Do the affected messages have a large amount of replies within the same email (in other words, senders and recipients replied to the same message many times)
If yes, here is a thread which has the similar issue: Bounce Back
PR_INTERNET_REFERENCES is a history of all message-ids that the message has been associated with. If you forward or reply, it will add the new message-id to the list. That will continue to grow if you continue to reply/forward the message. At some point, it exceeded the 64KB limit on the property. This is by design. So, the solution is to create a new message rather than reply/forward.
Please see if it applies to your situation.
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