I tried this in my Local machine , and am able send the notification to the participants(users).
check whether you set following properties.
In futuretense_xcel.ini file set xcelerate.emailnotification=true.
In futuretense.ini file set the following properties.
cs.emailaccount=Specifies the user account name to be used for sending outgoing mail. This is the account name(simply Username) on the SMTP server.
cs.emailpassword=Specifies the password for the e-mail account used by WebCenter Sites (specified by cs.emailaccount above property).
cs.emailhost=Defines the SMTP (e-mail server) host that is used by the ContentServer servlet to create and deliver e-mail messages.
cs.emailreturnto=Specifies the e-mail address from which mail is sent to all participants in workflow.
Note: while setting the properties make sure that " No Spaces" before/after the Value.
If above properties are set correctly, still mail not received. please upload your Sites.Log.
please Let me know if you have any issues.