Troubleshooting Outlook Express Error 0x800ccc90 Error Code: 0x800ccc90

When you try to check your email, you get the following error message:

There was a problem logging onto your mail server. Your User Name was rejected. Account: 'pop3.example.com', Server: 'pop3.example.com', Protocol: POP3, Server Response: '-ERR', Port: 110, Secure(SSL): No, Server Error: 0x800CCC90.

SYMPTOMS
When you try to log on to Microsoft Exchange Server with Outlook Express by using Secure Password Authentication, you may see the following error messages in Microsoft Outlook Express. Look in the Details of the Error tab after failing to connect.
* Unable to logon to the server using Distributed Password Authentication.
Account:'Company POP3 Server Accnt.',
Server: 'server.company.com',
Protocol: POP3,
Server Response: '-ERR The AUTH protocol exchange was canceled by the client.',Port: 110, Secure(SSL): NO, Server Error: 0x800ccc90, Error Number: 0x800ccc18
On the Exchange Server computer you will see the following Event IDs:
Application event log error:
13005 MSExchange Pop3 Authentication
Logon attempt by NTDomian\User from 157.57.148.24 to NtDomain/User has failed: EcGetMailboxDN() call failed with error The requested mailbox is not available on this server.

11310 MSExchange Pop3 Authentication
The following error occurred: The requested mailbox is not available on this server.

Cause:

* Incorrect Email settings.
* Incorrect scan settings on anti-virus software (if any).
* Corrupted account settings.

Solution

In Outlook Express, try using Clear Text, which is the Log on using option under the Servers tab of the mail account.
To do so:
1. On the Tools menu, click Accounts. This will bring up several tabs.
2. If you select any listed mail account, the properties will have a Servers tab with the Log on using option.
3. Select the Clear Text option.
If this works, then you were trying to access a non-existent mailbox or the wrong mailbox. If this does not work, then the administrator needs to check for and remove the custom recipient.

1. Check your Outlook Express settings.
2. Repair and Recover Outlook Express.

MORE INFORMATION

When a user tries to log on to Exchange Server with Outlook Express and Secure Password Authentication, the client will pass the credentials of the user logged on to the workstation. If the logon works using the Clear Text option: , the user will have to change his or her mailbox alias to the Windows NT account name in order to use Secure Password Authentication. This is because Secure Password Authentication will not pass the mailbox alias information. It defaults to and Exchange Server assumes the alias to be the Windows NT account.