SmarterMail 4.x Help
This documentation is for a product that is no longer supported by SmarterTools.

SmartHost Servers

SmartHosting allows one SmarterMail server to accept mail for another SmarterMail server. This can be used in a backup scenario so that if the primary mail server goes down, the secondary server will accept mail for it until the server goes back online. For more information about the roles of SmartHosting, please see Gateways and Other Server Roles.

To configure SmartHosting correctly, changes need to be made on the secondary server and to DNS records of domains that will have SmartHosting supported.

  1. Add SmartHosts - In the secondary server, add all IP addresses of the primary server to the SmartHost list. Mail that resolves to MX records that do not match these IP addresses or accounts on the secondary server will be rejected.
  2. Setup MX records - In DNS, add an MX record for the secondary mail server that has a LARGER preference value than the primary mail server. Refer to your DNS server documentation for instructions on adding MX records. Note: In MX records, lower preference value servers are tried first.
  3. Set appropriate retry times - Since the intent of SmartHosting is for the secondary server to be a backup server, adjust the retry times in General Settings to values that are more conservative. Good defaults would be: 10 minutes, 10 minutes, 10 minutes, 1440 minutes.

Note that it is good practice to disable the spool service on the secondary server if the primary server goes down for more than 30 minutes, then restart the spool once the primary server is back online. In this way, all messages will still be accepted through the SMTP service, but delivery will not keep trying to deliver the messages. Once you get the primary server online again, start the spool service on the secondary server and all the messages will start to be delivered.