If you send a reasonable volume of email, you've probably experienced the frustration of being told by some of the intended recipients that they never got your messages.

As service providers have implemented more stringent spam policies, legitimate email senders find that their emails often become collateral damage in the "War on Spam."

Fortunately, there are some simple things you can do that will usually help boost your email delivery rates - especially on popular email services like Hotmail and Yahoo.

Here are some free email authentication systems that I recommend to all of my clients.

  • DomainKeys Identified Mail (DKIM) adds a digital signature to the header of yours emails that enables the recipient's email server to verify that the email was really sent by your server. DKIM was designed by a Yahoo employee and Yahoo is one of the email providers that uses DKIM to validate the origin of emails received by its users.
  • Sender Policy Framework (SPF) allows you to add a special DNS record to your domain name that specifies what servers are allowed to send email using your domain name. An email server receiving an email can then check the sender's SPF record to verify that the server the email was sent from was authorized by you to send the email. SPF is widely used by popular online services, mail transfer agents (MTAs) and anti-spam applications/services.
  • SenderID is essentially SPF with a few additions. It is implemented by Microsoft (which owns Hotmail) so it too is well worth implementing. Most of the websites linked to above have information about setting up these systems and a qualified server administrator should have little difficulty in doing so.

One note - implementing SPF, SenderID and DomainKeys does not guarantee that your emails will be delivered, and does not eliminate the need to implement other best practices that minimize the risk of your emails being mistakenly identified as spam.

That said, in today's environment, not using these systems may unnecessarily make it more difficult for your emails to be received. If email delivery rates are important to you, you'll want to make sure that DKIM, SPF and SenderID become your friends and not your enemies.


Published 14 July, 2008 by Patrick Oak

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Comments (3)


James Steel

It's interesting to watch the profile of these technologies rise in the media since having the backing of the larger players.

I'm part of the team at Zen Software and we're a distributor of SecurityGateway for Exchange which includes the tools above and an array of others. The develoor Alt-N and MD Arvel Hatchcock Alt-N played an active role in the industry associations responsible for recommending these new standards.

SecurityGateway adds this security to Exchange servers, you can read about it here - http://www.zensoftware.co.uk/securitygateway/

about 10 years ago


Adam Grossman, President at Epostmarks, Inc.

These standards are important although like you mention don't provide any guarantee of delivery.

For truly high end deliverability one should employ the CertifiedEmail delivery platform which guarantees delivery to AOL, Yahoo!, Bell South, Time Warner, Comcast and Cox. Also consider ReturnPath that has very high delivery rates to MSN.

about 10 years ago


Patrick Oak, Blogger at Econsultancy


I might dedicate a future post to services like CertifiedEmail but those are not free and in my personal experience, I've never had a client that was willing to pay for such a service. This includes larger companies who really place a high emphasis on email delivery rates so my (admittedly limited) impression is that these are a tough sell for most companies.

about 10 years ago

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