You cannot log on to OWA because of ambiguous mailbox names

When you try to log on to a Microsoft Outlook Web Access (OWA) client, you may receive one of the following error messages:

Error message 1

Error message 2

Error message 3

The alias or user name that is specified may not be unique in the Microsoft Exchange Global Address List. Ambiguous names include any Last Name, First Last, or Alias that is entered in the logon screen that is equal to any Last Name, First Last, or Alias for any other mailbox. For example, John Doe's alias is jdoe, and Joseph Doenfron's alias is doe. If Joseph enters his alias in the logon screen, he will receive one of the error messages that is mentioned in the "Symptoms" section because of the ambiguity of his alias with John's last name as the server tries to resolve them.

This may occur if you join one or more sites that contain multiple users with the same alias or with the same display name. If an ambiguous (non-unique) name is detected, Microsoft Exchange Server cannot resolve the name to a specific mailbox, and error messages are returned.

When you create a domain account, try to avoid using names with similar prefixes and repeating suffixes. Try to create unique Windows NT domain logon names and unique Exchange Server mailbox alias names.

In Microsoft Exchange Server version 5.5 and later, you can enter the following fields for the user's mailbox:

• Alias - jamessmith
• Last Name - Smith
• First Last - James Smith
• Last First - Smith James
• Last, First - Smith, James
• user@domain.com - jamessmith@domain.com

For example, if a user's alias name is not unique, the user can enter his or her SMTP address. The SMTP address is more likely to be unique and provides for a greater chance of resolution. The user can then access his or her mailbox.

For additional information about what to do if you receive an error message when you use your SMTP address, click the following article number to view the article in the Microsoft Knowledge Base:

You can also use another method to work around this issue and to log on to OWA 5.5. You can use this method if the aforementioned workaround is not acceptable, or if you want to bypass the Logon.asp page.

After you specify your mailbox name and provide your credentials, Cdo.dll and Cdohtml.dll create dynamic URLs that the browser client uses to access Exchange information. These URLs are created only while a browser session is open with OWA and are cleared after you close the browser session.

You can create a browser shortcut that contains the URL to a specific user's mailbox to effectively bypass the Logon.asp page and to go directly to the user's Inbox. For the URL to function correctly, make sure that the name that you use to log on to OWA works correctly. If you are using this method because of ambiguous name resolution issues, this is very important.

To create a browser shortcut that contains the URL to a specific user's mailbox to bypass the Logon.asp page and to go directly to the user's Inbox:

1. Log on to OWA by using the alias name, the first and last name, the display name, or the SMTP address. After you find a logon name that works, go to step 2. Otherwise, repeat the process until you find a name that works.
2. After you log on to OWA, when you are viewing the Inbox, use one of the following methods:
   • In Microsoft Internet Explorer, click Send on the File menu, and then click Shortcut to Desktop.
   • Create a URL shortcut to the current page with your browser.
3. Open the properties of the URL shortcut, click the Web Document tab, and then change the URL to the following:
   http://Server_name/exchange/LogonFrm.asp?isnewwindow=0&mailbox=name
   Note Server_name is the name of the Microsoft Internet Information Services (IIS) or OWA Web server that is in your environment, and name is the name that is in step 1.

These steps create a shortcut that starts the browser and immediately prompts you for the credentials of the account that you specified in the URL. You can distribute this URL to the users who are affected by this issue. The users can put the URL anywhere that they may need OWA.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.