XCLN: Err Msg: No Transport Provider Was Available

• Microsoft Exchange Windows 3.x client, version 4.0
• Microsoft Exchange Windows 95 client, version 4.0
• Microsoft Exchange Windows NT client, version 4.0

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information on how to do this, view the "Restoring the Registry" online Help topic in Regedit.exe or the "Restoring a Registry Key" online Help topic in Regedt32.exe.

SYMPTOMS

This problem occurs with Microsoft Exchange Client in offline mode. When you reply to an SMTP message for which a custom recipient exists in the Exchange Server Global Address List (GAL), the following non-delivery report (NDR) is returned immediately:

   No transport provider was available for delivery to this recipient.

CAUSE

The Microsoft Exchange Server Internet Mail Connector (IMC) resolves the reply-to address as an internal Exchange Server mailbox when receiving mail from the Internet. When the IMC does a directory look-up and finds the sender's e-mail address in the directory, it replaces the SMTP address with the X.500 address. This makes the message appear as though it has been sent internally, and confuses the client when offline.

RESOLUTION

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall Windows. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" online Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" online Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

To resolve this problem, you must perform these steps on the computer running Microsoft Exchange Server (not on the client computer). There are different resolutions for Exchange Server versions 4.0 and 5.0:

Exchange Server 4.0

This fix allows verification of messages sent by certain Exchange users. The FROM address is compared to a list of users. If the address matches, the message is not delivered and an event log message is generated. It is also possible to save the message in order to identify the first SMTP host that was contacted.

1. Install Service Pack 3 and perform the following:

2. Stop the IMC.

3. Start Registry Editor (Regedt32.exe).

4. Go to the following key in the registry:

         HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services
         /MSExchangeIMC/Parameters
   

5. On the Edit menu, click Add Value and add the following entry:

         Value Name: TurfDir
         Data Type: REG_SZ
   

6. A dialog box entitled String Editor will be presented. Add the following information:

         C:\EXCHSRVR\IMCDATA\TURFDIR
   

7. On the Edit menu, click Add value and add the following entry:

         Value Name: TurfTable
         Data Type: REG_MULTI_SZ
   

8. A dialog box entitled Multi-String Editor will be presented. Add the following information :

         user1@site.domain
         user2@site.domain
   

   The Turf Table contains a list of e-mail addresses used to verify the FROM address on incoming Internet mail. They should be entered one per line with no extra spaces or delimiters. They are case insensitive. If a match is found, the message will be saved to the directory specified in the TURFDIR value.

9. Exit Registry Editor.

10. Restart the Internet Mail Connector service.

Exchange Server 5.0

1. Stop the Internet Mail Service.

2. Start Registry Editor (Regedt32.exe).

3. Go to the following key in the registry:

         HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services
         /MSExchangeIMC/Parameters
   

4. Edit the registry using Regedt32.exe and change the value for ResolveP2 registry key.

5. Highlight the value ResolveP2.

6. On the Edit menu, click DWORD and change the value from 0 to 1.

7. Exit Registry Editor.

MORE INFORMATION

The following are further aspects of the symptom:

• If Exchange Client is started online, and the same message is replied to, the "no transport provider" NDR does not occur.
• If you are offline and you reply to the message, and then retype the SMTP message exactly as it appears on the To line, the NDR does not occur
• Adding entries to the PAB or OAB does not change this behavior.
• If, after you click Reply, the properties of the To line are brought up, the properties show up as a Distinguished Name (it looks like any other native Exchange Client user), not as a PAB-type (SMTP) entry.