Ambiguous error if saving mailing without required field

Workflow:

1. Create New Mailing
2. Fill in all but one required field 
3. Save Draft
4. Error issued is "Sorry an error occurred and your information was
   not saved”

End user read this as a big issue, not an issue with having not set a recipient or title. Often end-users don't like to set the recipient group until the end of the process any ways.

There should be a validation check on the required fields, and issue an error/reminder accordingly.