Hi,
An excellent ETL tool like Datastage should not have this limitation. The notfication activity is used to fire any mails based on the jobs satus or any other requirment. But it does not support only dynamic mail body. You have to specify the mail body while designing the job. So the only thing is if you want to send some dynamic mail then we can put it only in attachment. Other wise we can use environmental variable but there is no use as we cannot go and assign and values to environmental variables.