3773259 - Email "The recipient's mailbox is full" from SuccessFactors

A candidate receives an email error message similar to this one:

Delivery has failed to these recipients or groups:
************** (system@successfactors.com)
The recipient's mailbox is full and can't accept messages now. Please try resending
your message later, or contact the recipient directly.

SAP SuccessFactors Recruiting Management 

The inbox related to the error is not SuccessFactor inbox but inbox were the users would receive their emails.
In this can you  need to check internally contacting you IT department

system@successfactors.com, "The recipient's mailbox is full"  , KBA , LOD-SF-RCM-EML , Recruiting Emails and Notifications , Problem