Windows XP Pro laptop with Office '97. Customer is happy using Outlook for email, but Lotus Notes is required for database access and testing. For some reason, Lotus becoms the default mail application only when using File .. Send to .. Mail Recipient from within Word or Excel. After much headache and misdirection, Regmon helps in locating registry key responsible for this action.

HKLM\Software\Microsoft\Office\8.0.. (sorry, i forgot the rest)
MAPIDLL and DLL32 with value c:\Program Files\Lotus\Notes\nmailman.dll

Apparently, Lotus decided to use the Enable MS Office 97 SendTo to Notes feature even though it is disabled in user preferences. After selecting this option, closing Notes, opening Notes and deselecting it again, the feature is now not active and Outlook is called correctly.

Below are a few items discovered during this fix:
Unable to Set Different E-Mail Programs for Different Users -Article ID : 315240

Set the default email client on a per-user basis

RE: Lotus notes not default mail program

 

 

( Windows XP Professional WinXP Pro 97 Excel Word excel.exe winword.exe )