Hi Taniya,
i think user don't have much idea about Query designer. most of the time they will refresh query analyzer and they may use free characters as they need.
if they want refresh when they need then you can give workbooks formate.
if they don't need that kind of manual work, then directly you can mail them thru using proper settings.
Below will be help to send thru mails.
http://scn.sap.com/docs/DOC-25391
Thanks