This article was previously published under Q130321
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Microsoft Mail for PC Networks attachments that are sent from simpleMessaging Application Program Interface (MAPI) applications should retainthe three letter file name extension as described in the Microsoft Windows3.x registry database. If the three letter file name extension is notmaintained, the application will not be launched correctly by accessing theicon associated with the object in the Microsoft Mail for Windows. Examplesof these extensions include .DOC (Word documents), .WKS (Excel worksheet),and .WRI (Write document).
If the three letter file name extension is not maintained in the code forthe MapiFile.FileName field (for Microsoft Visual Basic) in the MapiFilestructure, the following error will be returned from the Windows client:
No application is associated with the attached file FILENAME.EXT. Use the File Manager to create an association.
This error will occur even if Mail appears to display the application'sicon that the file belongs to correctly. This information will appearcorrectly because the information for the icon object is in the systemattachment WINMAIL.DAT. However, Mail does not use WINMAIL.DAT to launchthe application associated with the file. Instead, Mail uses the standardassociations found in the Windows 3.x registry database.
NOTE: MapiFileDesc is the equivalence of MapiFile in C.