Background
We are having users complain about links (<a href="...">) from our Outlook addin not opening in their default browser. Some see that Google Chrome (default) is opening, which is the intended behavior. But some see that IE is opening regardless of what the default browser is.
I suspect this may have something to do with the version of Outlook - but I haven't been able to pinpoint how and what. Maybe it has got something to do with the IE version on the computer since the addin window should be running in IE. Perhaps even the version of Windows. The users that have seen the issue so far is using Windows 10 Enterprise.
Questions
What version setup of Outlook / Internet explorer / Windows is required to have links open in the default browser instead of IE when opening a link from an Office addin?
How do I debug this?
Older versions of Outlook open IE by default. Please advise the users that are having issues to see if they have any updates.
Also, any domain included in the AppDomains element in the manifest will always open with IE.
来源：https://stackoverflow.com/questions/51951888/outlook-add-in-not-opening-the-default-browser-when-clicking-on-link-inside-the