The ROI of Implementing DKIM on Outbound Email


For any business that sends email to current or potential customers, becoming DMARC compliant should be a top priority. DomainKeys Identified Mail (DKIM) is a protocol that contributes to DMARC compliancy and enables a company to take responsibility for sent messages that can be verified by mailbox providers. Essentially, it allows the outbound domain to digitally sign email to provide legitimacy for the receiver via email headers. Although we realize there’s some reluctance and anxiety regarding its implementation, if your company hasn’t yet applied DKIM to all active domains/subdomains, MxToolbox strongly advises you to do so now.

Benefits of DKIM

DKIM’s all about reputation. If your business isn’t cryptographically signing its outbound messages, why should message recipients trust you? Nowadays, there’s simply too much risk in opening unsigned mail. On the flip side, if you’re currently DKIM signing emails, the recipient SMTP servers can be more confident allowing messages authenticated via DKIM to be delivered to the inbox, as DKIM is notoriously difficult to spoof. With DKIM implemented, your business’s on the right track to being protected from harmful spoofing and phishing attacks, which also safeguards your customer base.

In recent years, the DKIM protocol’s a method of email authentication that’s become increasingly popular with many ISPs searching for a cryptographic solution to the email forgery issue. Present evidence indicates that several ISPs now use it to filter mail based on whether the sender authenticates or not. In this case, a sender adds a digital signature within the email header that’s verified against a published key for the domain in question.

Moreover, many commonly used email clients (e.g., Gmail, Outlook, Yahoo!, and others) now check for a valid DKIM signature on incoming messages as a way of identifying the originator. When a mail server receives an email, it evaluates the DKIM header, then performs the following tasks:

  1. Retrieve public key from DNS of sending domain ( if sender’s
  2. Use key to decrypt electronic signature and verify content

In that sense, DKIM’s a beneficial method of increasing both your company’s email deliverability and sender reputation since it allows the receiving mail server to verify your reliability. Because DKIM’s becoming more prevalent in the email world, it’s wise (and advantageous) to not let your company overlook this technology.

DKIM Tools

At MxToolbox, the ins and outs of email delivery’s our passion. By providing a wide assortment of tools to help your business achieve optimal message deliverability, we believe you’ll be able to protect your brand and reach customers as intended. Specifically, our DKIM Record Lookup tool will test a domain name and selector for a valid published DKIM key record. Not to be outdone, our Email Deliverability option provides a comprehensive deliverability report by analyzing your headers, blacklist reputation of outbound IP address, and SPF records. These MxToolbox advances help identify any known issues related to DKIM. If your company’s wanting to receive the best possible feedback concerning email and achieve high delivery rates, implement the DKIM protocol today. As always, we’re here to help.