Gmail Tricks and Tips 4
16. Looking through your inbox for a mail that came with an attachment? Add has:attachment to your search query.
17. You can also search for mails that have specific filetypes as attachments, like this: has:attachment filename:doc.
18. By default, search only looks in your Inbox. To look for mail in other places, use the modifier in: For example, to search your Spam folder, add in:spam to your query.
19. To look for messages to or from people, use the to: or from: modifiers. For example, to find emails from someone called Jake, add from:jake to your search query.
20. You can exclude words from your search in the exact same way you exclude words from all Google searches, using the – symbol. For example to search for apples but not oranges, enter apples -oranges as your search query.