Before we can jump into how Backup Email works, let's quickly discuss the concept of Email Delivery...
When an email is sent to a recipient the email server looks to see which server handles mail for the domain using the DNS MX records. MX records specify which server(s) will receive mail for a given domain. Each MX record is given a priority (the MX level), the lowest number being the primary mail server. The primary mail server is responsible for delivering the mail to the appropriate user mailbox.
Mail delivery is first attempted to the primary mail server (indicated by the MX record with the lowest MX priority number). If that server is not reachable, then delivery is attempted to the mail server with the second lowest MX priority number. If the second lowest mail server in priority is unreachable, then the mail will be delivered to the server with the third lowest MX priority, etc.
DNS Made Easy's back-up email service provides access to three (3) additional enterprise email server clusters for complete email redundancy.
If your mail server cannot be reached, then your email is sent to DNS Made Easy's Enterprise Back-up email servers. Once it reaches our servers, it remains in queue and we continually reattempt delivery of the mail to your primary mail server. When your primary server is back online, the queued mail is instantly delivered to your mail server. DNS Made Easy will keep attempting to deliver mail to your server for 14 days or until it responds.
NOTE: DNS Made Easy DNS service for your domain is not required to use our backup mail services. You can add the appropriate MX records for your domain on any system.
Configuration consists of adding your domain into the DNS Made Easy web interface, as well as adding the additional MX records provided to your domains DNS records. If your domain uses DNS Made Easy DNS service, this can be done automatically.
The DNS Made Easy back-up email service is not an anti-spam service. However, we do perform simple email checking to help prevent spammers from using our emails servers as an open relay to your mail servers.
Verify the server sending the email has correct reverse DNS configured.
Check to make sure the "from" mail address is valid.
Check to make sure the email headers are properly formatted.
Utilize the Spamhaus RBL as well as an internal RBL
* Greylisting is a simple method of defending electronic mail users against e-mail spam. It is the best way of blocking most spam without using content filters, which can cause false positives. In short, a mail transfer agent that uses greylisting will "temporarily reject" (a 450 error code) any email from a sender it does not recognize. If the mail is legitimate, the originating server will try again to send it later usually within a few minutes, at which time the destination will accept it. If the mail is from a spammer, it will not be retried so the spam will not be relayed through our systems and on to your mail server.