+
+.subsection "ODMR customer connection" SECTODMRCUST
+.cindex ODMR customer
+Exim supports the &"customer"& side of ODMR,
+with a command-line option &"-atrn"& that requests a connection
+to a given host, issuance of an ATRN command then operation
+in SMTP server mode.
+The option must be followed by two arguments.
+
+The first is the name or IP of the provider to be contacted.
+
+The second, which may be empty, should be a comma-separated list
+of domains for which mail is to be requested.
+Interpretation of the list is up to the provider;
+an empty list is expected to result in some default being returned.
+
+The provider host is placed in &$domain$& for routing;
+router and transport must be configured suitably to make the connection.
+For example:
+.code
+begin routers
+to_odmr_provider:
+ driver = manualroute
+ condition = ${if eq {$atrn_mode}{C}}
+ route_data = <;$domain
+ transport = call_provider
+
+begin transports
+call_provider:
+ driver = smtp
+ port = odmr
+ hosts_try_auth = *
+ command_timeout = 10m
+.endd
+
+Note that the specification requires a long timeout for the ATRN
+command, to allow for scanning of queued messages.
+
+Configuration should also include client-side authentication
+and processing for receiving messages.