How to remove old Delegate from Outlook

--> For some time now we had ongoing issues with "sometimes" (in beginning seemed random) people would receive Non-Delivery messages stating a person's name who no longer works in the company and they swear they never sent an email to them. Back and forward we tried to narrow it down and to troubleshoot.
Originally we assumed one of the old outlook rules is involved - it wasn't the case, however.
Later on, we found out such error messages occur only if meeting invite is sent to one specific manager.
Checking his pc for outlook rules and attempt to clear them brought nothing. Someone suggested checking it's possible to be an old delegate set in outlook.
Even thou if we didn't found any in his outlook, that idea did put us on the right path, and later-than-sooner :) after extensive googling I found a solution, as like usual forums were my friends ;-)
Environment:
Client:  Microsoft Outlook 2003, Server: Microsoft Exchange 2003 with SP2
The Problem:
A person who used to work and was set as a delegate to that manager was removed from Active Directory, before changing the Outlook delegate settings, and such she was no longer appears in the delegate list.
Other people seem to have the same problem as well (here)
Solution:
Here is what I found after a long and tiring search on forums:
The rule which defines delegate isn’t magically going away after the user has been deleted from AD, in fact, it stays hidden in outlook settings and it’ll take a very special tool to change it.
I found at least two such tools, one commercial – OutlookSpy , which I tried but didn’t particularly like since it’s gives so much information it’s overwhelming for regular Joe SysAdmins like me J
The other one, free: Microsoft Exchange Server MAPI Editor available here for download.
The included Doc explains the steps, but seems to be written for experts, so let me help you, my dear colleagues.
The Steps:
From Top Menu - > Session-> Logon and Display Table [and pick the right outlook profile]
Right Click on Mailbox – “user name”-> Open Store
Expand the tree: Root Container -> Top of Information Store
Right Click on Inbox-> Display Rules Table
Look for the line with blank for Rule name and “Schedule+EMS Interface” in PR_Rule_Provider. This is the rule for a delegate. Right-click on that line and delete it.

All done!

And of course, with such low-level tools you can plenty of damage to your exchange profile, so be careful and smart what you are doing.
Don’t say Bored SysAdmin didn’t warn you :) as-in-much I bear no warranty or responsibility on any adverse results caused by using the information above.