Managing Categories during e-mail exchanges

By default, categories on incoming e-mail are removed, and categories are removed when replying to or forwarding an e-mail. This setting allows you to control how categories are shared as users exchange e-mail messages. You can specify that categories are not removed for users' incoming e-mail. You can also specify that e-mail messages that users reply to or forward retain the categories on the original message.

Accept Categories assigned to incoming mail by the sender

Registry Hive	HKEY_CURRENT_USER
Registry Path	software\policies\microsoft\office\16.0\outlook\preferences
Value Name	msoridolacceptcategories
Value Type	REG_DWORD
Default Value	0
True Value	1
False Value	0

When replying to and forwarding mail, include personal categories

Registry Hive	HKEY_CURRENT_USER
Registry Path	software\policies\microsoft\office\16.0\outlook\preferences
Value Name	sendpersonalcategories
Value Type	REG_DWORD
Default Value	0
True Value	1
False Value	0