Recently a customer was getting the error code; 0x80070005-0x000004dc-0x00000524 when trying to email ‘sent as’ from a newly created shared mailbox.

After searching online I found a lot of potential solutions like;
– Make sure only Full Access and Full control are set as permissions, do not use sent on behalf aswell.
– Start Outlook in safemode
– Create a new Outlook profile
– Use the OWA

The only thing that worked was using the OWA, but then I saw that ‘Show in global addresslist’ was set to ‘No’. When I changed this to ‘Yes’ it was working again!

I hope this helpes you out and saves you some time.