This is the server side error - meaning the server reports it to Mail.dll. There is nothing you can do about it.
It seems that it has some problems processing this message. It is very strange as it shows the message id, while the error is 'Unable to retrieve rfc822msgid'
The only thing you can do is report that to your server administrator, google search revels this is a common Gmail problem.
Of course, as you have full message id, you could delete this message, to prevent your POP server from rising this error again.