Seemingly at random, we get this error when trying to send an email with an attachment:
msg - upload not found: d0f30118-8102-42fa-94a2-513fe9e365f6:e4124d56-f890-4335-bea4-8f90cca4d290
code - mail.NO_SUCH_UPLOAD
method - ZmCsfeCommand.prototype.invoke
detail - soap:Sender
data - [object Object]

It doesn't happen every time, but it has gotten more and more frequent lately. What steps should I take to debug/resolve this problem? Should I file this as a bug report, or has it been resolved previously and my searching didn't find the resolution?