Do I assume the windows XP the forum detected is or is not the operating system.

What operating system, 32 or 64 bit?

Good morning Matt. Apologies, XP SP3, 32 bit.

You could try reinstalling Thunderbird to refresh the relevant mapi DLL registration. MAPI in XP 32 bit is fairly bullet proof. In latter Windows versions Microsoft have removed it and it must be manually added. Even then 64 bit operating systems have issues.

At this time it appears a 32 bit operating system for 32bit Thunderbird and 32bit programs is the way to go. Unfortunately professional operating systems at 32bit appear to be almost a special order.

Hi Matt, have tried that umteen times. Even uninstalled MYOB and reinstalled it. Got no joy.

what is the MAPI error exactly?

Do you know the version that actually worked for you? Perhaps a little backward updating might shed some light.

All 5 systems on the network run Thunderbird 32 and MYOB Accountright 19.8. 4 of the systems can email invoices, purchase orders and statements. Only 1 pesky system stopped being able to!.

The actual error message is: An email session could not be started. Please check your MAPI settings.

try re-registering the mozmapi DLL that is in the Thunderbird program folder.

http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/regsvr32.mspx?mfr=true

The reinstall should have done that, also use regedit and see if any other versions of mozmapi are registered.