Email failed warning when "Do not save sent mail" selected

VMPro default installation on CentOS. Domains hosted in VMPro.

When a user has personal email preferences set to "do not save sent mail" when they send an email in usermin they get this error: "Failed to send mail : Failed to set IMAP flags : Error in IMAP command UID: Invalid arguments." The mail actually goes through to target.

If they change their preference to "Save sent mail" the error message does not return.

If I change the default setting in usermin module config to "save sent mail" and turn off ability for user to modify that preference, the error message returns.