E-Commerce Configuration Guide : Site Configuration Settings : Email Settings : MailSubject
 
MailSubject
Key value:
Any text
Description:
Used to populate the Subject field of the confirmation e-mails from your site. The wwSale_id is appended to the end of the text used here. The default value is Sales confirmation - Sale # , which is usually adequate because the sale number automatically gets appended to this in the Subject line of the e-mail.
Example:
MailSubject = Sale Confirmation - Sale #
See also:
MailFromName
MailFromAddr
MailCC
MailBCC