If searching doesn’t find the right emails in Mail on Mac
If you don’t get expected results when you search for email messages in the Mail app on your Mac, try these suggestions.
Mail may not be looking in the Trash or Junk mailboxes, or searching encrypted messages. To include them when searching all mailboxes, choose Mail > Preferences, click General, then select the options.
You may need to sync the mailboxes on your Mac with those on the mail server. Choose Mailbox > Synchronize > [account].
The Mail folder (located in your home Library folder) may be excluded from Spotlight searching. To check, choose Apple menu > System Preferences, click Spotlight, then click Privacy.