It is default in this registry setting Computer\HKEY_CURRENT_USER\Software\Clients\Mail

I should have added it is windows 10.

There is a mapi32.dll involved and it is messy, but I suggest you reinstall Thunderbird. While that is rarely an option, in this case you will be rewriting the registry components and certainly the path the the MAPI dll used for MYOB.

Also make sure the outlook setting to make it the default mail client is turned off. Otherwise it will reset itself on each start.

Check that Thunderbird option to check if it is the default mail client is turned on.

Ty matt. First I opened/setup outlook and then unchecked it being the default. Then closed it down.

Reinstalled thunderbird. Tried MYOB. and Outlook opens to send the email

I am sort of guessing, but knowing the way Microsoft office leaves things in memory (mail notifications etc), my guess is you only "think" you have closed outlook.

Try this stuff https://support.microsoft.com/en-au/help/2591170/why-does-outlook-not-appear-on-the-desktop-while-its-process-is-runnin

I would guess they even have stuff in the startup group so a reboot might not clear it.

You are persistent!!! TY! But it didn't work.

As you said it seems to be a mapi32.dll issue.

I worked through this article with no joy.

http://kb.mozillazine.org/MAPI_Support

There is another setting you can check:

• Exit Outlook
• Start Thunderbird

• Control Panel > Default Programs > Set program access and computer defaults

• click on 'Custom' and select the arrow to show contents of custom

Under 'choose a default email program' section

• Look for 'Outlook' and uncheck the checkbox that says 'enable access to this program'
• select 'Use my current email program'
• For 'Mozilla Thunderbird': check the checkbox that says 'enable access to this program'
• then select 'Mozilla Thunderbird' and the checkbox will go grey.
• click on 'OK'

I wondered if this was due to the program you use, so I checked out MYOB here: http://help.myob.com/wiki/display/supar/Setting+your+default+email+program+or+email+address#expand-WhichemailprogramscanIusetosendemailsfromAccountRight

AccountRight only supports Microsoft Outlook 2007 - 2016 (32-bit). If you usually send emails via a web email service, such as Gmail, you can most likely access and send those emails from Microsoft Outlook via IMAP or POP.

If you don't use Microsoft Outlook, you can save your document as a PDF (Send To > Disk) then attach it to an email in your preferred email software.

Thanks Toad. But I had worked through all your suggestions before coming here.

I will add the article above from mozilla suggests the problem is with 'sloppy programming' of thunderbird regarding mapi.

The solution I eventually hit on was using a unwieldy tool from microsoft to force the install program of Office to only install what I wanted. (no selections or de-selections options offered during install.) https://www.youtube.com/watch?v=FoVtGmTTVPM&list=LLMZVhOVDXSxb8XkMs5WOnhA

Thanks for all your help.

I have little faith in the mozillazine article. Issues upon issues have been growing over recent years with MAPI. It appears to work mostly on Windows 32 systems and sometimes on windows64 systems. Microsoft have said it is deprecated technology but not really offering anything else.

I spent some time looking at bugs, but this is not an area that makes for easy comprehension or understanding. The following two might offer some insight, or at least some registry keys to look at.

https://bugzilla.mozilla.org/show_bug.cgi?id=618678 https://bugzilla.mozilla.org/show_bug.cgi?id=547565

As a intermediate tech. I can usually fiddle around and get things to work. Preference is that they just work. But so many lines of code easy to get things wrong. On top of that, operating system manufacturers have agendas coded into their software, with the latest versions locking everything down so you have to wade through the registry file to change things.

I am not sure what the problem's source... what I see is a favorite piece of software of mine (thunderbird) isn't keeping up. I can see that in the near future... I will say goodbye to it, as it will require too much effort to resolve conflicts like above. Thanks again everyone for the help.