Can we add custom icon in mailbox from outlook web add-in office.js

[Rajnish-Asite]

I need to add custom icon in outlook mailbox from outlook web add-in office.js library as given in below SS

I have tried with singleValueExtendedProperties & Office.context.mailbox.item.loadCustomPropertiesAsync() method to load & set custom property but still I am not able to set custom Mapi Property "http://schemas.microsoft.com/mapi/proptag/0x10800003"

Please do needful.