You'll need to post an example full raw email here (including errors) for us to attempt to replicate. Make sure you censor any sensitive info like email addresses, ip addresses, etc.
I will say a few people have reported this in the past but we could never replicate the issue so I don't know where the issue lies. If we can replicate it then we can debug and address the issue. But so far all of the examples people are providing work fine in my testing.
Cheers.