To fix MYOB emailing invoices open regedit and go to HKEY_CLASSES_ROOT\Interface\{00063001-0000-0000-C000-000000000046}\TypeLib and ensure there is only 1 subkey
Outlook 2007 – Version 9.3
Outlook 2010 – Version 9.4
Outlook 2013 – Version 9.5
Outlook 2016 – Version 9.6
Outlook 2019 – Version 9.7
If there is a wrong subkey higher than the one you need, delete it.
For Excel go to HKEY_CLASSES_ROOT\TypeLib\{00020813-0000-0000-C000-000000000046}\TypeLib and check the same.