It is good to eliminate a single point of failure when dealing with SMTP communication both inbound and outbound. There are avenues that can be taken to help eliminate that possibility by installing two or more GroupWise Internet Agents (GWIAs) into a GroupWise system.
A GroupWise Internet Agent must be installed as a subordinate to a domain, so this will require installing a new secondary domain if one does not exist already.
There is nothing additional on the GroupWise side that needs to be configured to provide inbound redundancy other than installing a new GWIA. The redundancy is handled by adding a second MX record to DNS to reflect the inclusion of a second SMTP server.
A good example to see how a DNS MX record looks and works can be seen by using a tool such as NSLOOKUP and querying for MX records. An example of results is shown below for a lookup against gmail.com
Default Server: modem.lan
> set type=mx
gmail.com MX preference = 40, mail exchanger = alt4.gmail-smtp-in.l.google.com
gmail.com MX preference = 5, mail exchanger = gmail-smtp-in.l.google.com
gmail.com MX preference = 30, mail exchanger = alt3.gmail-smtp-in.l.google.com
gmail.com MX preference = 10, mail exchanger = alt1.gmail-smtp-in.l.google.com
gmail.com MX preference = 20, mail exchanger = alt2.gmail-smtp-in.l.google.com
The preference listing in the third column determines the order in which SMTP servers will attempt to send messages to a server. The lowest preference number will be tried first and if a failure to connect occurs, the next will be tried and so on. This DNS setup will make sure that if a server is down or unavailable, then the next will be tried.
To help re-route mail out an alternate GWIA in case of a server down situation, there are couple of items that need to changed or confirmed in the GroupWise Administrator.
1) All links to the GroupWise Internet Agent MUST be set to TCPIP. To check this setting do the following:
a) Open the GWIA object in the GroupWise Administrator
b) GroupWise | Agent Settings | Message Transfer Port
c) Change the port to something other than 0 and any number that is not likely to conflict with any other existing process.
By changing this to a port, the MTA will attempt to communicate with the GWIA over TCPIP and will detect when the GWIA is down. When the setting is set to 0, the MTA uses file transfer and does not know when the GWIA is down.
d) Save the changes
2) Set an Alternate GWIA on a domain by domain basis.
a) Open the domain object in the GroupWise Administrator
b) Internet Addressing | Internet Agent for outbound | Check the Override box
c) Choose the primary internet agent for outbound (this likely will not need to change from what is displayed)
d) Choose the Alternate GWIA in case the default GWIA is down.
e) Save the changes
After doing steps 1 and 2, you will want to restart all GWIAs and MTAs that are effected. You will want to check the http console of the MTA to make sure that the links are open to the GWIA.
1. Bring down the primary GWIA (You should see in the MTA http console that the link to the GWIA is closed)
2. Send a message to an internet address outside of your system.
3. The message should route to the secondary GWIA and out of your system