Hi brandon.ross, I don't think Thunderbird has the ability to intercept a communication from Office to Outlook (I guess that's from one part of Office to another part of Office). This may be a problem with a Windows 10 setting or an Office setting. You might consider asking on Microsoft's forums.

jscher2000,

Thank you for replying quickly, I appreciate that a lot. Funny story, I actually already am working with Microsoft support and we are scratching our heads over here as to why just Thunderbird performs like this. Everything in Windows is set to Outlook and I've even changed a few of the default associated file types in Thunderbird to Outlook but still no luck. So not to shoot down your response, but Thunderbird does have a way to "intercept a communication" from the Office apps, otherwise it wouldn't be taking priority over Office and Windows.

Are there any settings you may know of that I could take a look at? Or any reccomendations of things to try outside of the basics that I've been through. (Update Windows, Outlook, Thunderbird, set defaults, etc)

Well, this is only an analogy, but on the hyperlink side, Office can cling to a removed browser even when the system default is correct. This article describes the relevant registry settings:

https://www.slipstick.com/problems/this-operation-has-been-cancelled-due-to-restrictions/

You could ask Microsoft whether they know of similar settings related to the "Share" feature you're using in Excel.

I see what you are getting at. It could be due to some bad cached information on the computer as well. I know that is general as heck, but in my testing, I did get Outlook to open once but I have no bloody clue what configuration I used or what I did differently. I really appreciate the recommendation. Those MS guys are always iffy about regedits, but I'll give this a go and see how it works. I'll let you know how it goes when I can test this off my work computer.

Thank you again jscher2000. Ill keep this thread updated as best I can

It appears that TB is still registered as the default client for MAPI operations, i.e. for emailing a file from another app such as Word, Excel etc. I suggest you uninstall TB, restart Windows, and then open Settings in W10 and check that Outlook is set as the default email app and also for all options when you select 'Set defaults by app'. Uninstalling TB won't affect your data in the separate profile folder, but if you install TB again, make sure to not set TB as the default during the installation.