You can search the To, From, Subject and body text of email messages. Mail searches the
downloaded messages in the current mailbox. For iCloud, Exchange, and some IMAP mail
accounts, you can also search messages on the server.
Search email messages: Open a mailbox, scroll to the top, and enter text in the Search field. Tap
From, To, Subject, or All to choose which fields you want to search. If your mail account supports it,
messages on the server are also searched.
Mail messages can also be included in searches from the Home screen. See “Searching” on page 29.