SPF is an important email authentication method that reduces spammers’ success rates online. Email authentication protocol SPF defines which mail servers and applications are allowed to send from your domain. There are many factors that can cause SPF soft failures, SPF hard failures, and other SPF failures.
- What is SPF?
- Ways SPF fails
- Conclusion
What is SPF?
SPF is a TXT record published in your domain hosting provider’s DNS settings.
Every email you send must pass through spam filters and firewalls. It’s like a police checkpoint. The cops will first look at your DNS settings for a valid SPF record. If you do, they’ll check your insurance policy and see if you’re listed as an authorized driver.
When a sender sends an email, their mail server checks the From address to see if the IP address or email service provider can send mail for that domain. SPF will pass if the IP address is listed as a valid sender.
SPF authentication fails if the sender’s IP address is not listed in your SPF record. To prevent email spoofing and unauthorized IPs from abusing a domain’s reputation, many ISPs blacklist IP addresses that fail SPF too frequently.
When SPF fails:
- The domain has multiple SPF records
- DNS failure to resolve domain name
- a single SPF check involves more than 10 DNS lookups
- A single SPF check involves more than two void lookups
- no SPF record on the domain
- the SPF record is incorrect
- the IP address is not on the SPF list
Ways SPF Fails
1. SPF Neutral
SPF neutral means the domain’s SPF record explicitly states that it does not claim that the IP address is authorized. The ‘all’ mechanism is used.
2. Error SPF (SPF Permanent Error)
SPF PermError occurs frequently when domain errors occur. It’s the fact that SPF login usually fails. The receiving MTA invalidated your SPF record while you were performing DNS lookups.
SPF allows for a maximum of 10 DNS lookups, each of which returns an error. The MTA is a regulated industry, so SPF breakup could have a big impact. SPF supports DNS lookups. The SPF file cannot have more than 10 DNS lookups.
3. TempError (SPF Temporary Error)
A DNS error, such as a DNS timeout, occurs during an SPF authentication check by the received MTU. It’s usually a temporary error with a 4xx status code that causes SPF failure but later passes. The error returns a status code of 4x, which can be repeated.
4. The SPF Failure Preventer
SPF (Sender Policy Framework) errors can be avoided by publishing SPF records for all tools and applications used to send email from your own domain.
Use our Uptime Monitor to be notified if your SPF, DKIM, or DMARC records are down. Stay out of spam and improve email deliverability.
Conclusion
Some tools let you monitor SPF, DKIM, DMARC, IP Blacklists, and more. These tools were created to help you improve email deliverability. Therefore, make sure you use the right tool.