DKIM email signing for Mercury hosted email

If you use for SMTP, DKIM signing can now be configured from the Control Panel. We’ve also added TLS connections on outbound Mercury email too. Coupled with our existing use of SPF (Sender Policy Framework) on all outbound Mercury email, you should see even better mail delivery performance.

What is DKIM?

DKIM email signing provides a way for mail recipients to validate that the email they receive purporting to be from your domain, really is coming from your domain. When you send an email that is DKIM signed, the recipient’s email server can be confident that your email is genuine. This means less email ending up in spam filters, and more email reaching your contacts on time with the minimum of fuss.

The use of DKIM and SPF can also make a visual impact for some recipients, see the example here of how Gmail alerts users when email is not signed, and when it is:

The red question mark means Google weren’t able to confirm the sender


When the red quesiton mark is replaced by a generic or custom avatar, the email has been authenticated


How does DKIM work?

Much like SSL, DKIM uses a private/public key system to validate email. The private key is stored securely and is used to compile a hash of email headers, which in turn are then stored in the header of the email itself. The other component is the public key which is stored in the publicly accessible DNS record for your domain name – and is used by the receiving mail system to decrypt the header of your arriving email, and to check that no contents have been modified on their way to their destination.


How to enable DKIM on your email

Enabling DKIM on your outgoing mail is simple and can be enabled with one click of a mouse button. For full details on how to do this, check out our Knowledge Base article ‘How to activate DKIM signing’.

Stuart Melling

Hi! I am the the co-founder of and Business Development Director; I've been at this hosting lark for more than twenty two years, ulp.. I oversee multiple areas of our business to ensure products and services are meeting our customer's needs. You can get in touch over on LinkedIn or replying to any of most posts. In my spare time I am exceptionally interested in food and drink, I run several food website and am a multi-award winning, food and drink writer.

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