Down here in Oz, probably the most popular small business accounting package is MYOB. It includes features where it will email invoices, statements, payment advices etc provided the PC has a mapi compliant email package. In the days of GroupWise 6, the products worked together well. Since GroupWise 7 this got rather flaky, in my experience.
Just recently (running GW8) on Windows 7 Pro, I briefly fixed the problem by reinstalling WMS.exe (1790KB V4.71.1015.00 dated April 26,1999). Before that I had tried - unsuccessfully- wms.exe that shows as 1907KB V4.72.2929.0 dated May 11, 1998 - though I think that might be a Win95/98 version. So I thought I had solved it. Two days later and PC reboots seem to have 'broken' it again, though after a second reinstall of the V4.71.1015 wms.exe it is working again, even after one reboot.

I can't keep fixing this after every second reboot, and I certainly can't ask my client running GWise 7 to do this every time they start their PC.

Does anyone have a suggestion? Wash your mouth out if you're going to suggest using Outlook as the client...