The mail resolver cannot resolve some recipient email addresses. This failure indicates that there is misconfiguration of ...

The mail resolver cannot resolve some recipient email addresses.  This failure indicates that there is misconfiguration of an outgoing mail.

One or more parameters given to the mail resolver for the recipients did not have email address attributes.  This could be caused because the parameter did not resolve to a User object or because the User object does not have a valid email address.

Ensure that the parameter which configures mail recipients resolves to User objects and that all User objects have valid email addresses.
 
The specific parameters to investigate are included below:
{0}