Monthly Archives: June 2019

Keeping your Verified Sender List updated

Did your accounting department add a new billing vendor? Or, did your Marketing department decide to try out a new email marketing solution?

These common situations often lead to email delivery problems that can go unnoticed until after you learn that no one has been receiving your email for some time. In many cases, those making these changes are unaware of the importance of maintaining and updating their business’s email focused DNS records, let alone understanding what DNS records are.

Now, imagine those two examples repeated over and over again as new vendors come and go, other departments expand, or business infrastructure changes. The result? Unknown email delivery problems that will cost time and money and hurt your brand.

Manage your SPF Record

If your business sends email, then we hope you have an SPF Record setup for your domain. If you don’t have SPF and you are sending email you will need to get a record setup asap!  If your business utilizes third parties to send email, SPF is mandatory for your email to reach it’s destination. Keeping SPF updated and correct across all email domains is an important task that needs attention. If the SPF Record is missing a sender or is mis-configured,  a receiving mail server or cloud-based email service (e.g., G Suite, Microsoft Office 365) may block the message from being delivered.

One of the most challenging aspects of email is managing this ever expanding list of senders that are used across multiple departments and/or vendors of your business. This has a real work impact as most businesses only realize too late that their SPF record needs to be constantly updated with each vendor or internal service they add over time. Until customers start asking where your emails are or your email revenue drops you probably won’t even think to ask questions like: Did our administrators start using a third-party email provider without telling us? Are the sales team still using that lead software or did they switch to Salesforce? Better yet, probably almost no one will ask…has anyone updated the SPF record to be current?

Basically, the “too many cooks in the kitchen” expression applies to this situation. This is where having an email partner like MxToolbox makes a lot of sense. Taking MxToolbox’s years of email expertise and Delivery Center service, your team will immediately know  when these type of problems occur, long before you notice the revenue drop or get customers calling in.

Can You Have Too Many Senders?

In the 2019 world of email, most businesses send email through a number of vendors (think Office 365, MailChimp, Salesforce, etc.) along with their own systems. After a certain point having too many senders becomes a major problem. To put it bluntly, email servers will reject your mail, every single piece of it. Known to email admins, the 10 lookup rule with SPF records has become a real problem for businesses that use multiple email services.

Use That will be three (6) lookups. Send marketing email with Sendgrid? Thats another one (1). Send trouble tickets via Zendesk or website status updates through Thats another two (2). We’re already at nine (9) lookups and thats only using a small subset of vendors. With all these vendors, now that limit of 10 doesn’t seem so hard to hit.

The really scary part is that nearly all businesses are unaware there is a limit and when they exceed it. This lets good mail get rejected, losing your business valuable revenue from your email program. To prevent situations like this from happening, MxToolbox monitors your senders as part of the Delivery Center service. Add too many vendors – we’ll alert you to that instantly.

Sending from Subdomains too?

Often overlooked when sending email is the importance of unique SPF records for every subdomain that sends email. Do your marketing campaigns come from Then you might require a unique SPF record.

For example, a business sends email via two (2) domains: and To ensure that email will be delivered, both of the two subdomains need to have their own SPF record. Failing to add a SPF record for one of the domains may lead to delivery problems. This requirement continues in the event the business decides send email from other domains, such as the company’s marketing department decides to start sending marketing promotions via

This problem with subdomains often occurs from how easy it is to spin up a subdomain for a unique campaign or maybe a department function. Do your customers get invoices from For this reason many businesses hit this pitfall with SPF and only later learn about the problem, after revenue has been lost in the process. With those three (3) examples plus your business’s primary domain that’s four (4) domains that need unique SPF records.


Keeping an eye to all the scenarios described above can seem a daunting task. This is where a partner like MxToolbox comes in to help.  With our years of email expertise and Delivery Center software, we can make sure your business is alerted to these types of situations long before they become email crippling problems.


Why are my messages not getting delivered?

Unless you’re an IT professional, you might not understand the ins and outs of email delivery. As your business continues to grow, it’s important to ensure your messages are delivered as planned to the intended inboxes. For companies that rely on email correspondence to expand their brand, knowing the intricacies of email delivery is a necessity. MxToolbox is your expert on an often-overlooked aspect of electronic communication deliverability: functioning SPF and DKIM.

Importance of SPF and DKIM

For your email delivery rates to be as high as possible, your first need to keep your sending IP addresses off of blacklists.  Now, correctly implementing Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) is crucial to email delivery. The SPF protocol is an email validation method designed to limit spoofing. SPF allows you to publish a list of IP addresses that are authorized to send on behalf of your domain.  Receiving mail exchanges verify that incoming mail sent from a domain comes from an IP address authorized by that domain’s administrators.  Major inbox providers, like Gmail, Yahoo! and, scan email to validate that the sending IP is included a sender’s SPF record.  If not, the email can be rejected.

DKIM allows a sender to cryptographically sign an email, essentially claiming ownership.  DKIM also helps to combat spoofing.  When a recipient inbox provider receives an email, they can check the signature against a public key published by the sender.  If everything checks out, then the inbox provider knows the sender authorized the email.  Failed emails may be rejected.

By keeping an updated list of active outbound domains/providers that your company uses to send messages, you will be practicing good email hygiene.  You are removing one of the key reasons email is rejected – senders not listed in your SPF records.  Knowing which senders are and are not utilized creates a more organized approach to email deliverability and enables you to configure SPF and DKIM more accurately.  In addition, you cannot ignore the importance of monitoring your IP blacklist reputation.

If you accidentally misconfigure your SPF and/or DKIM protocols, your messages may be quarantined or outright rejected by inbound providers.  Incomplete/erroneous records, new senders missing from SPF implementation, and providers not handling DKIM properly are just a few of the issues that could derail your email delivery efforts if the SPF/DKIM mechanisms aren’t correctly applied. Identifying and resolving these issues equates to a simplified workload for inboxes to recognize your emails are legit and they come from a trusted domain.

MxToolbox is the Email Delivery Expert

MxToolbox provides everything you need to curate your outbound email provider list, analyze your email reputation, and setup SPF, DKIM and DMARC moving forward.  With a variety of insightful and comprehensive products available, MxToolbox is the clear choice to address your email delivery needs. Contact our experienced team to discuss how to best maximize your message delivery rates and expand your company’s brand.