You need to do port forwarding on the ASA's outside interface ip for port 25 to be able to achieve the desired objective. Modify the following statement (remove the redundant "destination eq smtp" from it):object service smtp  service tcp source eq s...

Thanks Marvin

Will there be problems if I take the passive node down, install the aip  ssc-5 and boot it up, because they are not identical hardware wise? Yes, this understanding is correct. We need to arrange some downtime to be able to carry out this activity. ...