FWIW, this is our (current) checklist for MAPI problems:

The 64-bit version of Outlook does not work with our program.

0. Make sure that there is a default mail client installed. (Control Panel->Internet Options->Programs)

1. Make sure that all three VPE DLL's are present in the Programs folder: vpep3271.dll, vpejnip3271.dll, and vpejniguip3271.dll. Check that the Start In folder is correct on the shortcut used to start the program.

2. Check the following in the registry:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Messaging Subsystem

Make sure that the following string values are present:

CMCDLLNAME32 Mapi32.dll
OLEMessaging 1

Two files containing the registry entries are attached to this article. These files can be imported into the registry instead of adding them manually.

3. Check to make sure that the MAPI32.DLL is present in the C:\Windows\System32 folder.

4. In Windows Explorer, can you right click on a file, go to Send To, and is the Mail Recipient option present and enabled? Does it work?

5. Try installing Thunderbird and make it the default email client. Make sure you restart the Datatech Accounting Software so that it will register the new email client program. Go to Tools->Program Setup->Main->Fax & Email Settings and make sure that the "Resolve Email Address to Address Book (MAPI)" box is not checked. This option doesn't work with Thunderbird.

Note: Under 64 bit versions of Windows, when you change the Windows default email client, it may make a change to the following registry key:

HKEY_LOCAL_MACHINE\Software\Clients\Mail:default registry value

But it may not change this key:

HKEY_LOCAL_MACHINE\Software\WOW6432Node\Clients\Ma il:default registry value

Check the registry to make sure the 32-bit default client has been changed. (Reported under Windows 10)

Check to make sure the MAPI DLL for Thunderbird can be registered with REGSVR32:

C:\Program Files (x86)\Mozilla Thunderbird>regsvr32 /i "C:\Program Files (x86)\Mozilla Thunderbird\MapiProxy_inuse.dll"

6/29/17 - On Graham, we got the following message:

[Window Title]

The module "C:\Program Files (x86)\Mozilla Thunderbird\MapiProxy_inuse.dll" was loaded but the entry-point DllInstall was not found.

Make sure that "C:\Program Files (x86)\Mozilla Thunderbird\MapiProxy_inuse.dll" is a valid DLL or OCX file and then try again.


There are multiple reports of Send to Mail Recipient not working on version 52 of Thunderbird, Try version 45.8:


Sometimes we exhaust this list and resort to using SMTP email functions built into our program and tell the customer the preview emailing functionality can't be enabled.