by default latest version of opencart does not allows to save multiple emails at setting->setting->store
Extra email setting mod allows to save multiple email ids.
In the OpenCart admin backend, do the following steps:
Go to Extensions > Extension Installer
Upload the extra-email-setting-1-0.ocmod.zip
Go to Extensions > Modifications
You should see an entry for this extra-email-setting
Click on the Refresh button (top right of the page)
If during the install you get an error saying "Could not connect as ......"
while uploading this zipped extension via the Extension Installer,
you probably have the FTP support disabled from your hosting.
In that case you may try the following OpenCart Extension Installer fix first: