Your web hosting or email server can go down any time because of maintenance, hardware, software or OS crash, Data center network failure etc. If emails from your visitors are utmost important to you, then you should definitely consider using a backup email service.
How Normal Email Delivery works?
As you can see in above table, each entry has a priority assigned to it. Whenever someone sends you an email, delivery is first attempted to the primary mail server i.e. the entry with lowest priority number (ASPMX.L.GOOGLE.COM.). If that particular mail server is down, then delivery is attempted to another server with second lowest priority (ALT1.ASPMX.L.GOOGLE.COM. or ALT2.ASPMX.L.GOOGLE.COM.).
If the second mail server is also unavailable, then email will be delivered to the server with third lowest priority (ASPMX2.GOOGLEMAIL.COM. or ASPMX3.GOOGLEMAIL.COM.). This process continues depending on the total number of MX entries (with ascending priorities) you have for your domain.
If all the mail servers are unavailable, then mail delivery will be delayed or will be permanently failed. The email will bounce back to its original sender with mail errors:
This is where backup email service comes into action.
How Backup Email Service works?
Backup email service is generally provided by third party websites by paying them either on a monthly or yearly basis. The server or mail clusters of these services are completely isolated from your hosting server as well as data center.
If all the mail servers are unreachable in your account, then all your emails are sent to the backup server. Once they reach there, they form a queue and the server continuously tries to deliver them to your primary mail server. When your server is back online, all the emails in the queue are delivered to you.
Every backup server keeps on attempting mail delivery to your primary mail server for a certain number of days. After that the mail bounces back to its original sender and you should seriously consider changing your hosting or email provider.
How to set up Backup Email Service with your Domain?
For setting up a backup email service with your account, you are required to associate your domain with the backup server and then you need to add additional MX entries in your domain’s DNS record.
You will receive these additional MX entries, when you have successfully signed up with your backup email provider. They will also give you access to your email control panel.
I have personally used DNS Made Easy and it’s one of the best and cheapest available service as of now. If you are considering signing up with them, then keep following limitations in mind:
- Only 1 GB of Email data OR 100,000 messages in the queue are allowed for a single domain. If your requirement is higher than this, then for an additional price 3, 5 and 10 GB options are also available.
- You are only allowed to transfer 10 GB of email data per month.
- A daily cap of 100,000 incoming connections per day is imposed on each account. This is done to prevent dictionary and directory harvest attacks.
Additional features of the service:
- It will verify the authenticity of sending mail server by checking whether it has correct rDNS configured (Reverse DNS Resolution).
- It makes sure that the FROM address is valid and the email headers are properly formatted.
- The service make use of Greylisting, which protects your account from email SPAM without using any content filters! If a service is utilising Greylisting, then it will temporarily reject an incoming email from a unrecognised sender with a 450 error code (user’s inbox unavailable, try again later). If the mail server is legitimate, then it will try to deliver the mail again and this time the destination server will accept it. Spam servers never tries to resend an email!
- It utilises Spamhaus RBL, which tracks spammers and various types of SPAM related activities.
You can check out articles on configuring your backup service right here.
While writing this post, the pricing for the service is $12.95 for 1 Year for a single domain. If you have a Reseller account or want to buy backup service for lots of domain names, then you should directly contact DNS Made Easy.