Managing the Links between Domains and Post Offices
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10.1.3 Link Protocols for Direct Links
The link protocol of a direct link between domains determines how the MTAs for the domains
communicate with each other across the link. When you create a new domain, you must link it to an
existing domain. This creates the initial domain-to-domain link.
Between a domain and a post office, the link protocol determines how the MTA transfers messages
to the post office. Messages do not flow directly from one post office to another within a domain.
Instead, they are routed through the domain. When you create a new post office, you must specify
which domain it belongs to. This creates the initial domain-to-post office link.
There are three link protocols for direct links between domains and between a domain and its post
offices:
“TCP/IP Links” on page 149
“Mapped Links” on page 149
“UNC Links” on page 150
NOTE:
On Linux, TCP/IP links are required.
TCP/IP Links
“Domain-to-Domain TCP/IP Links” on page 149
“Domain-to-Post Office TCP/IP Links” on page 149
Domain-to-Domain TCP/IP Links
In a TCP/IP link between domains, the source MTA and the destination MTA communicate by way
of TCP/IP rather than by writing message files into queue directories. The source MTA establishes a
TCP/IP link with the destination MTA and transmits whatever messages need to go to that domain.
The destination MTA receives the messages and routes them on to local post offices or to other
domains as needed. During the process, message files are created in the
gwinprog
directory for
backup purposes and are deleted when the TCP/IP communication process is completed.
Domain-to-Post Office TCP/IP Links
In a TCP/IP link between a domain and a post office, you must configure both the POA and the
MTA for TCP/IP. The source MTA establishes a TCP/IP link with the destination POA and transmits
whatever messages need to go to that post office. The destination POA receives the messages and
delivers them into mailboxes in the post office. During this process, message files are created in the
POA input queue for backup purposes and are deleted when delivery is completed.
Mapped Links
“Domain-to-Domain Mapped Links” on page 149
“Domain-to-Post Office Mapped Links” on page 150
Domain-to-Domain Mapped Links
In a mapped link between domains, the location of the destination domain is specified in the
following format:
