On June $1,$ Kareem sends Fatima an e$-$mail offering to build her a new garage for $$30,000.$ In his e$-$mail, Kareem wrote, "acceptance by certified mail is advisable." On June $2$ at $8$ a$.$m$.,$ Kareem sends Fatima a letter by certified mail attempting to revoke the offer. At $2$ p$.$m$.$ the same day, Fatima mails Kareem a letter via certified mail attempting to accept his offer. Under these circumstances, $\_\_\_\_\_\_\_\_$