hey, thanks but i done with changes in alfresco-global-porpetties.
mail.host=smtp.hostname
mail.port=25
mail.protocol=smtp
mail.username=abc(valid username)
mail.password=xyz(valid password)
mail.encoding=UTF-8
mail.from.default=abc(vaild email id)
mail.smtp.auth=true
but still me getting error "0 invite sent out, 1 failure".
plzzz help me, may b there is another way by which i cn slove this problem.