>>Hi Naomi,
>>
>>>
>>>Do you have ideas how to turn printer to print Duplex programmatically? In Windows XP?
>>>
>>
>>Do you need to update printer preferences for the session and/or permanant printer settings? Or is this for a report, just before printing and/or stored as part of the report's printer environment?
>
>Bo,
>
>I need to print letters double-sided using MailMerge from Word (Excel file as the DataSource) for the particular letter (about 2000 letters).

You can retrieve a DEVMODE structure of a Printer using DocumentProperties (http://msdn.microsoft.com/en-us/library/ms535735.aspx). Then set the dmDuplex attribute of the DEVMODE structure (http://msdn.microsoft.com/en-us/library/ms535771.aspx). Then use the SetPrinter (http://msdn.microsoft.com/en-us/library/ms535488.aspx) function to update the printer properties. There is something similar in this article: http://support.microsoft.com/kb/140285/EN-US/

However, I'm not sure that this is what you are after from your description. Are you asking how to change someones printer settings at the O/S level so that you can print one letter in duplex mode?

If you are using Word, you may be better off finding a Automation way of solving the problem or save the Duplex attribute with the document via the "Document Page Setup".

All of this is outside the scope of what I have done in the past.