We are requesting a centralized area of results for a search. So that we can just do one-time searching for the keyword, this can save the user's time on searching on all databases.
This means a single page / area that can show the search result from all local and server-side databases that the user has access to them.
Lastly, this is not just for mails, calendars, and contacts. We want to search all documents that contain the keyword. Currently, you need to search the keyword in databases A/B/C separately, this is time-consuming.