# Restart When mail won't flow (gets stuck on OWA Drafts folder)
No change. Looking in the event logs, I see a mountain of red. That is never a good thing! I notice event id 3003 -- MS Exchange BackEndRehydration. The NT Authority\System does not have token serialization permission.
Something got tightened down or changed. Our first suspect: permissions. According to Microsoft KB Article 2898571, this is often due to effective deny permissions on the ms-Exch-EPI-Token-Serialization user right on the computer object. Groups that are DENIED ms-Exch-EPI-Token-Serialization user right are:
* Domain Admins
* Schema Admins
* Enterprise Admins
* Organization Management
Check the group membership via group policy (run this cmdlet:)
gpresult /scope computer /r
UGH! the computer is now part of the Schema Admins security group. I removed the computer from that group and everything is fine.
For the sake of completeness, the Exchange computer should be a member of these five groups: