Having migrated from Exchange 2003 to 2010 (SP2), we are experiencing this issue with one or two mailboxes.
When you attempt to remove or edit a delegate, the message 'The Delegate settings were not saved correctly'. Cannot activate send-on-behalf-of'
I've read about checking the user security setting for self - settings are correct compated to other users
Looked into installing the hotfix or creating a local registry (more of a workaround) entry but for us this does not seem to be a solution if people are using a mixture of PC/Terminal Services.
Since the majority are ok, what needs to be done for the individual mailboxes on Exchnage to remedy this once and for all?
Thanks