NewUserFAQ:MultMailServer
From Greenview Wiki
The basic SpamStopsHere service already adds a lot of redundancy and reliability to your email system by assigning you multiple load balancers for your domain located in multiple data centers in multiple geographic areas of the U.S.A. and storing (or queuing) email for your domain should your email server become unavailable. For most clients that just have a single email server, signing up for our service increases the reliability of your Internet email exponentially. Some organizations also have a backup email server that will queue the email for their primary mail server if it should become available. This backup email server is completely replaced by the SpamStopsHere service, allowing you to appropriate the resources elsewhere, saving money.
However, some enterprise-sized businesses will actually have a backup or hot standby email server that is a live mirror of the primary one. Alternatively, your organization may have multiple email gateways (more than one public IP address for your email service, due to redundant Internet connectivity). In this case, you would typically want those delivering email for your domain to try the primary email server first, and then any additional ones, depending on availability. This is typically done with your domain’s DNS MX records, but you lose this important function after signing up for our service, because you must point all of your MX records to us, and then you tell us what one place to relay your email to after it’s been filtered for spam and viruses.
When you sign up for our Enterprise Edition, however, you can let us know if you have multiple mail servers that you want your mail sent to. Currently, we would send such mail to you in a “round robin” fashion, with mail being evenly distributed to your mail servers (if you have 3 mail servers, roughly a third of your mail we be sent to each server in an alternating fashion) or a "failover" fashion, which would send all emails to your main mail server until the point it became unreachable. Then, the messages would go to your backup server.
