Unable to cast COM object of type 'Microsoft.Office.Interop.Outlook.ApplicationClass'

This may be the cause of office itself.

Please try following solution, it worked for me! May be you have 2 or more versions of office installed in your computer, in registry. you have to choose one and delete one.

Cause:

The registry on this machine contains a key for an older version of the Outlook View Control.  
It was leftover from a previous Microsoft Office  installation.

Resolution:

Close Outlook.
Open the registry editor by running REGEDIT.
From the highest level, do an export to make a backup of the registry, just in case.
Locate the key: HKEY_CLASSES_ROOT\Typelib\0006F062-0000-0000-C00-000000000046
Within that folder, there will be two keys: 1.0 and 1.1 (1.0 is from an older version of Office,  1.1 is from Office 2010)
Delete the 1.0 key: HKEY_CLASSES_ROOT\Typelib\{0006F062-0000-0000-C00-000000000046}\1.0
Close the registry.
Reopen Outlook 

This is from linke Redirecting

And I found in my computer there 1.1 and 1.2 key, but 1.2 was blank. So I delete 1.2 and reopen outlook, it worked. And Uipath could send out outlook email normally.