The void lookup limit was introduced in RFC 7208 and refers to DNS lookups which either return an empty response (NOERROR with no answers) or an NXDOMAIN response. This is a separate count from the 10 DNS lookup overall count.
As described at the end of Section 11.1, there may be cases where it is useful to limit the number of "terms" for which DNS queries return either a positive answer (RCODE 0) with an answer count of 0, or a "Name Error" (RCODE 3) answer. These are sometimes collectively referred to as "void lookups". SPF implementations SHOULD limit "void lookups" to two. An implementation MAY choose to make such a limit configurable. In this case, a default of two is RECOMMENDED. Exceeding the limit produces a "permerror" result.
This is meant to help prevent erroneous or malicious SPF records from contributing to a DNS-based denial of service attack.
Your Email Deliverability is in Jeopardy!
Blacklisting is a sign that you are not actively managing your email deliverability. Other technologies - SPF, DKIM and DMARC are now just as important to get your email placed in the Inbox of your recipients. If you aren’t managing email deliverability, your message may never be heard.
MxToolbox Delivery Center Features:
- Insight into your SPF, DKIM and DMARC configuration to ensure your sending email properly
- DMARC Compliance checks for all of your reported email
- Adaptive Blacklist Monitoring of all your email senders
- Recommendations for improving DMARC compliance and DMARC policies
- Event-based reminders for emergent issues and on-going maintenance
DMARC is a necessity for your business!
Learn More about Email Delivery