Unable to uninstall Exchange 2000/2003 Server

When we try to remove an Exchange Server, it fails stating the following error.

The easiest way to check if there are any mailboxes exist in Exchange system Manager, is to check under mailbox store - mailboxes. If you do not find any mailboxes - this means that there are certain users who have mail enabled attributes however have not accessed their mailboxes ever. The way to find those users are.

First Method:

1) Need to open Active Directory Users and Computers.
2) Right click on your domain.
3) Select Find
4) Click On advanced tab.
5) Click on Field - User - Exchange Home Server.
6) Select Condition as "Ends With"
7) Within Value Type your Exchange Server Name.
8) Click on Find Now.
9) For finding those users better - select View - Choose Columns - scroll down to X500 - Click on ADD and close.
10) You should be able to find those users as per the picture below.
11) You should be able to find their location in AD using this output - next would be to mail disable them using Exchange Task on the user.

Second Method:
IF the first method does not help you, please install Windows Support tools on your Exchange Server.
Go to Start Run type adsiedit.msc
Expand
=> Configuration
=> Services
=> Microsoft Exchange
=> Organization
=> Administrative Groups
=> Your Administrative Group Name
=> Servers
=> Your Exchange Server
=> Information Store
=> Storage Group (containing Mailbox store)
=> On right hand side - go to properties of Mailbox Store.
=> Go to attribute HomeMDDBL
=> Here you would find the list of mailboxes those exist on your Mailbox Store - you should be able to find their location in AD using this attribute - next would be to mail disable them using Exchange Task on the user. (See picture below)

 Third Method:
If the above two methods do not help, we will now search the entire AD with all its users. contacts, groups etc and their attributes.
1) Open Command prompt and type in csvde -f C:\output.csv (as typed in picture below)

2) Once the output file is created - open it in Excel, only keep two columns rest can be deleted / removed.
a) DN (First Column)
b) msExchHomeServerName.

Having both these columns - create an Auto Filter by using Data - Filter - AutoFilter (in Excel).
(It should look like the picture below)

3) You should be able to find their location in AD using this Excel sheet - next would be to mail disable them using Exchange Task on the user.

Using any of the above methods if you succeed Exchange should get uninstalled smoothly.