Transport mapping lookup tables
transport_maps
The parameter specifies optional tables with domain to (transport, nexthop)
mappings. See Transport mapping for syntax details.
By default, this feature is disabled. Specify the types of databases to use.
Sensible possible values:
- dbm:/etc/postfix/transport
- hash:/etc/postfix/transport
- hash:/etc/postfix/transport, nis:transport
- hash:/etc/postfix/transport, netinfo:/transport