I know this issue has come up in the past, but the only solution I've seen for it is to disconnect from Zimbra and log back in again. This isn't working.

I have a user who receives emailed faxes via Verizon Document Delivery. For every fax she receives she also gets an Error 403 Must authenticate. Its not debilitating, but it is very annoying. Does anyone have an idea how to make it go away?