You need to have that email address set up on your server -- whatever it is. Let's say your domain is called yourbes4.com
You would go to the control panel of your hosting company account and set up a mail account for support@yourbes4.com
Then, assuming all is well with your WordPress application and you've entered THAT email address in the settings for the e-commerce plugin (I've never used it but there should be some setting or option to provide an email address for any tasks requiring notification of store owner)... the plugin uses your EMAIL application to send you email.
You would set up your local computer's email application to get all mail for that account, just as you would if you wanted to get your gmail email locally on your computer without having to use a web interface to do it.
It may be that the ecommerce plugin has a mail interface, I don't know. Any technical support for plugins (particularly paid-for plugins) is generally asked and answered at the site FOR THAT PLUGIN.
What is the exact plugin? (no generalizations... where did you download the plugin from?) Do you have a real email account set up for the one you are attempting to use? No matter what you put into WordPress's general settings for admin email, if that account doesn't exist for your domain, then it won't work.
HTH