Hello Smarterfan! I'd recommend checking the folder permissions of the SmarterMail MRS directory to ensure SmarterMail can write to the attachments/uploads directories. Things are a little different in how we access things in current versions compared to where you're at now, but if you're running this as an IIS site you'll want to make sure that identity associated with the SmarterMail application pool has full control over that MRS folder.

Tried your suggestion, no change.  Anything else I can try?

Hi Smarterfan,

You may want to try upgrading to at least the latest minor version of 8.x, which is 8.4.4359.  See if an upgrade helps.

Ok... any significant risks associated with that move?  

There are no risks with doing this minor upgrade that I'm aware of.  Of course even with a minor upgrade you should do a full backup before starting.  Here's our kb article with instructions for the upgrade: Minor Upgrade of SmarterMail.