Gmail use way:how to search mail you need.
1.“has:attachment”——search the mails contained the attachment.For example”has:attachment from:me label:sent
2.“filename:pdf”——search the mails contained *.pdf.For example “filename:rar” or “filename::zip”.
3.“before:2006/01/01 label:sent”——the mails sent before 2006/01/01.for example”after:2006/01/01 label:sent”
4.“from:abc@def.com”——search all mails from abc@celn.net