We’ve talked about SPF Limits and SPF Flattening in the past. There is simply too much demand to get into the SPF record. Whether it’s adding a new sender or an existing sender updating and include, senders sometimes necessarily and sometimes lazily add too many lookups into your SPF record. In fact, one well-known CRM goes so far as to write dynamic macros in their SPF record to avoid hitting the 10 include limit.

What is the issue?

Currently, reddit has published an SPF record with too many includes, meaning that during email delivery, the last includes to be checked are dropped. This could leave one or more of reddit’s legitimate senders appearing to be spam or phishing because email from these senders will fail SPF Authentication.

In addition, reddit is running a DMARC policy of “reject”. While it is up to the individual Inbox Provider, a DMARC reject policy instructs the recipient systems to reject email that is not DMARC compliant, which means trashing any email that fails SPF Authentication. Essentially, there is an unknown amount of email from reddit that cannot be delivered, potentially affecting accounts, customers, purchases, etc.

What can they do?

There are several ways to get your SPF record below the 10 lookup threshold:

• Manual or Automatic SPF Flattening as discussed in our blog.
• Reducing the number of senders.
• Splitting email sending across multiple domains or subdomains with separate SPF records.

All of these options have pros and cons. Many senders do not want to lose the cache of their primary domain, some cannot consolidate vendors to reduce SPF complexity, and some SPF records cannot be easily manually flattened. Even if you get below the threshold today, vendors may add new includes to their SPF records tomorrow pushing you over the threshold again.

What’s going to happen?

With a proper DMARC reporting and management system, like MxToolbox Delivery Center, they should already be seeing SPF failures and working to fix their SPF record. In the short-term, reddit will see some of their email bounce, in the long-term, this could cause their domain to have serious reputation issues.

How can MxToolbox help?

You first need to know if you have a problem before solving it.  MxToolbox offers a Free SPF Lookup Tool where you can check your real-time SPF configuration for errors, including the risk of “Too Many Includes”.  We also have a suite of Email Delivery tools to help you manage DMARC, SPF and DKIM and get your email to the Inbox.