The ThinkAutomation Mail Server can be used as a backup mail server. What this means is that if your main mail server is down, messages will be delivered to the ThinkAutomation mail server. ThinkAutomation will then forward the messages to your main mail server when it is back up.
Using the Mail Server Options, select the Backup Mail Server tab.
Enter the Domain Names that you want ThinkAutomation to act as a backup mail server for.
In the Send To Server column you can specify the DNS name or IP address of the mail server to forward the messages to. Leave this entry blank to use the first mail server specified in the MX record for the domain.
You will need to edit your MX record and add the IP address of the ThinkAutomation PC. Make sure this has a lower priority than your main mail server.
Should You Use A Backup Mail Server?
Many experts now recommend against specifying backup mail servers in your MX records. The reason is spam. Unfortunately spammers now send most of their emails to the backup mail server found in recipients MX records. The backup mail server then sends the emails on to the primary mail server. The primary mail server is likely to trust the backup mail server, meaning the spam could get through. Most senders will re-try sending you an email if your primary mail server is down anyway - so the usefulness of backup mail servers compared against the extra spam threat is now negligible.