ASA version 9.6(3)1 

both nat have same configuration except 172.16.100.2 use interface, anyone have same question?

this object work fine

object network 172.16.100.3_25_xx2
 nat (DMZ,xyz) static 202.175.xx.203 service tcp smtp smtp

this object not work
 object network 172.16.100.2_25_xx1
 nat (DMZ,xyz) static interface service tcp smtp smtp

 Cisco Adaptive Security Appliance Software Version 9.6(3)1
Device Manager Version 7.2(2)1

Compiled on Thu 30-Mar-17 21:40 PDT by builders
System image file is "disk0:/asa963-1-smp-k8.bin"
Config file at boot was "startup-config"

packet-tracer input xyz tcp 8.8.8.8  1024 202.175.xx.202 25

Phase: 1
Type: ROUTE-LOOKUP
Subtype: Resolve Egress Interface
Result: ALLOW
Config:
Additional Information:
found next-hop 202.175.xx.202 using egress ifc  identity

Phase: 2
Type: NAT
Subtype: per-session
Result: ALLOW
Config:
Additional Information:

Phase: 3
Type: ACCESS-LIST
Subtype:
Result: DROP
Config:
Implicit Rule
Additional Information:

Result:
input-interface: xyz
input-status: up
input-line-status: up
output-interface: NP Identity Ifc
Action: drop
Drop-reason: (acl-drop) Flow is denied by configured rule

# packet-tracer input xyz tcp 8.8.8.8  1024 202.175.xx.203 25

Phase: 1
Type: UN-NAT
Subtype: static
Result: ALLOW
Config:
object network 172.16.100.3_25_xyz
 nat (DMZ,xyz) static 202.175.xx.203 service tcp smtp smtp
Additional Information:
NAT divert to egress interface DMZ
Untranslate 202.175.xx.203/25 to 172.16.100.3/25

Phase: 2
Type: ACCESS-LIST
Subtype: log
Result: ALLOW
Config:
access-group xyz in interface xyz
access-list xyz extended permit tcp any host 172.16.100.3 eq smtp
Additional Information:

Phase: 3
Type: NAT
Subtype: per-session
Result: ALLOW
Config:       
Additional Information:

Phase: 4
Type: IP-OPTIONS
Subtype:
Result: ALLOW
Config:
Additional Information:

Phase: 5
Type: INSPECT
Subtype: inspect-smtp
Result: ALLOW
Config:
class-map inspection_default
 match default-inspection-traffic
policy-map global_policy
 class inspection_default
  inspect esmtp _default_esmtp_map
service-policy global_policy global
Additional Information:

Phase: 6
Type: FOVER   
Subtype: standby-update
Result: ALLOW
Config:
Additional Information:

Phase: 7
Type: NAT
Subtype: rpf-check
Result: ALLOW
Config:
nat (DMZ,xyz) source dynamic any interface
Additional Information:

Phase: 8
Type: NAT
Subtype: per-session
Result: ALLOW
Config:
Additional Information:

Phase: 9
Type: IP-OPTIONS
Subtype:
Result: ALLOW
Config:
Additional Information:

Phase: 10
Type: FLOW-CREATION
Subtype:
Result: ALLOW
Config:
Additional Information:
New flow created with id 538894, packet dispatched to next module

Result:
input-interface: xyz
input-status: up
input-line-status: up
output-interface: DMZ
output-status: up
output-line-status: up
Action: allow