Monthly Archives: September 2019

SPF Tool and IPv6 Updates

SPF Tool and IPv6 Updates

To continue our support of Email Delivery and Deliverability, MxToolbox is adding IPv6 support (Internet Protocol Version 6) to our SPF Tool, with more tools to come online later. When a user runs an SPF lookup, this update changes the lookup behavior for MX and A records that are specified within an SPF record (as tags).  Now,  SPF lookups will also check for AAAA DNS records and their resulting IPv6 addresses. Previously, the SPF tool only looked for IPv4 addresses when MX and A tags were present in an SPF record.  


IPv6 is the most recent version of the Internet Protocol—the communications protocol that provides an identification and location system for computers on networks and routes traffic across the Web. It was ratified as an Internet Standard in 2017 and allows for larger addressing space. Every computer, smartphone, and any other device connected to the Internet needs a numerical IP address in order to communicate with other devices. Compared to its predecessor, IPv6 can handle packets more efficiently, improve performance, and increase security.

While, IPv6 has been around for decades, IPv6 addresses are now being actively used in email delivery.  MxToolbox is here to help with the transition to IPv6.  MxToolbox’s research of the current outbound email space shows that adoption has largely been among the free webmail providers such as Gmail and  Additionally, 25% of the Alexa Top 1000 websites are currently reachable over IPv6 networks.



The ROI of Implementing DKIM on Outbound Email

For any business that sends email, becoming DMARC compliant should be a top priority. DomainKeys Identified Mail (DKIM) is a protocol that contributes to DMARC compliance and enables a company to take responsibility for sent messages by signing them cryptographically.  Recipients of DKIM-compliant email can then verify incoming email by the signature.  Essentially, DKIM establishes a trusted relationship – recipients know who the sender is because the sender is taking responsibility for the email.   While implementation might be complicated, if your company has not implemented DKIM for all active domains/subdomains and with all sending systems, you may be risking your email deliverability.

Benefits of DKIM

DKIM is all about ownership. If your business isn’t cryptographically signing its outbound messages, why should message recipients trust you? You aren’t taking ownership of what you send.  In today’s environment, there is too much risk in email.

On the other hand, if you are currently DKIM signing emails, your email is more likely to be delivered.  Recipient email servers are more confident allowing DKIM-signed messages to be delivered to the inbox, as DKIM is notoriously difficult to spoof.  With DKIM implemented, your business is in a better position and more protected from harmful spoofing and phishing attacks, which also safeguards your customer base.

In recent years, the DKIM protocol has become increasingly popular with many ISPs.  Major inbox providers like Yahoo! and Gmail were early adopters for outbound emailing.  Now, many ISPs use DKIM authentication as a method to filter incoming mail. 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.

When a mail server receives an email, it evaluates the DKIM signature in the message header and then performs the following tasks:

  1. Retrieve the public key of the sending domain via DNS lookup
  2. Use the key to decrypt the electronic signature in the email header
  3. Verify the hash value for the content

In that sense, DKIM is 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. As DKIM’s prevalence grows, it’s wise (and advantageous) to adopt this technology.

DKIM Tools

At MxToolbox, email delivery is our passion. We provide a wide assortment of tools to help your business achieve optimal message deliverability to protect your brand and reach customers as intended. Our DKIM Record Lookup tool will test a domain name and selector for a valid published DKIM key record. Looking for a more comprehensive analysis?  Our Email Deliverability tool is a comprehensive deliverability report that analyzes your headers, blacklist reputation of outbound IP address, and SPF records. MxToolbox helps you identify any known issues related to DKIM. To receive achieve high delivery rates, implement DKIM today. As always, we’re here to help.