Retrieve and read old sent emails

[leigh32]

Sent email to my accountant w/attachment of my quickbook acct.  She could not open it.  Suggested I go back

into my sent emails.  She said I sent it in Aug 2011, when I go back into sent it stops in Sept 2011.  How do I

go back farther?????  Very important, computer where this work was done is fried!!