Prolateral Consulting Ltd
Prolateral Consulting Ltd
SMTP Inbound protection
Backup MX Mail Server
Email Disaster Recovery

Prolateral offers primary and backup domain (DNS) services, with servers in key geographic locations providing the best service possible.

BackupMX - FAQ

Please see below some frequently asked questions regarding BackupMX.

Backup MX is a service provided by Prolateral which gives you the ability to add a secondary (backup) SMTP server to your domain and act as a failover if your primary server becomes unavailable.

An MX (Mail eXchange) record tells email servers how to delivery email to your domain.

Typically when you register a new domain several records are created for you. One of these records is the MX record so emails can be delivered to your mail server.


MX records have two values associated with them.

The first is a priority number. The lower the number the more important the server (also called the primary mail server). If that server is unavailable then mail will attempt delivery to the next server with the next higher number. So lower the number higher the priority of server.

The second value is the server name. Please note the server name must be a fully qualified domain name, and that record must equate to an A record. CNAME records are not supported

So with multiple MX records you provide a more fault tolerant solution for email delivery.

You can sign up for Backup MX by clicking here and be up and running within minutes.

Sign up now for Backup MX

Using command tools like NSLOOKUP or DIG you can retreive your current MX record settings


nslookup -q=mx

dig -t mx


But you will need to have purchased a domain with someone.


As long as you have a domain and access to the DNS (Domain Name Service) records so you can update the MX records you will not need to transfer your domain name, unless you want to.


But you will need access to the domain name providers DNS manager so you can update the MX records.

If your company has its own DNS servers, talk to your DNS administrator. Otherwise, contact your domain name provider.

If you want to use Backup MX then YES!

By using Backup MX and adding the second MX record you have increased your fault tolerance on email delivery, because if your server goes does down the backup smtp server will accept your emails until the primary is restored.


As long as you enter the MX records correctly, you won't lose any MX records. While your MX records are changing over, some mail will be delivered using your old MX information, and some mail will be delivered using your new MX information, but all of it will be delivered.

backupMX will keep emails queued for up to 7 days. After 7 days if the email can't be delivered to the primary mail server the email/s will be bounced as undeliverable.

If your primary server is going to be offline longer than 7 days, then we can force the delivery of queued emails to a different location (raise a support request for this). Note, it is your responsibility to ensure that the alternative mail server is configured correctly to receive your emails, otherwise you will lose any emails queued on backupMX.

If you type the incorrect delivery information in the MX record, some mail will bounce. The sender will receive a notice that the mail wasn't delivered.

If this happens, correct the MX records as soon as possible.

The standard backupMX service is designed to queue up to 1Gb of email or 100,000 messages (Which ever is reached first).

Larger options are also available for domains with large volumes and/or sizes of email.

By default emails will only be queued for a max of 7 days, if you're going to be offline longer then please contact us to discuss extending that period for you.

Greylisting is a simple method of defending users against spam email. It is a great way of blocking most spam without using content filters.

Greylisting will “temporarily reject” (a SMTP 450 error code) any email from a sender it does not recognise. If the email is legitimate the originating server will try again within a few minutes, at which time the email will be accepted. 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.

More information on Grey Listing can be found here.

RBL stands for Realtime Block List or Realtime Black List.

RBL servers are used, run and hosted by spam filtering companies like Prolateral which contain a realtime list of IP Addresses of servers that are known to generate spam.

If you no longer want to use the BackupMX service you can cancel at anytime from within the secure clients area.

In the Secure Clients Area select the menu 'My Services'. Find the desired service you wish to cancel and select it. Then click on the button 'Request Cancellation'.

You will also need to remove the MX record from within your domain names DNS settings, please see the setup section or the support pages for additional information on setup and removal of the BackupMX service.


Does what it says it does on the tin. Provides us with a SMTP Backup service.

Angela Dugham, Newcastle, Tyne and Wear