iCloud
Search for emails in Mail on iCloud.com
You can search for messages containing specific text.
In Mail on iCloud.com, click the folder you want to search in the sidebar.
If you don’t see the sidebar, see Show or hide the sidebar in Mail on iCloud.com.
Click in the search field above the message list, type the text you want to find, then select the field you want to search in.
To exit the search and see all your messages again, click the Delete button
in the search field.