The Zimbra web client is not allowing attachments to be sent.
I've checked in the Admin console and the attachment size is set
to 10MB. This is the error I see in the popup notification. The attachment
being sent is 5MB.

msg: Message exceeded allowed size
code: mail.MESSAGE_TOO_BIG
method: ZmCsfeCommand.prototype.invoke
detail: soap:Sender
data: [object Object]