‘SPF validation failed’ is a response that you come across when the SPF record corresponding to your company domain has some errors. These syntax and configuration mistakes invalidate your SPF TXT record, allowing a malicious sender to exploit your business domain name for sending spam and phishing emails, impersonating someone that recipients would easily trust.
Let’s understand what happens when SPF fails and how you can sort out this problem to safeguard your organization.
What Does SPF Validation Error Mean?
Before you know how to fix an SPF validation error, you should know why does it occur in the first place. This way, you’ll be cautious with your SPF record management drill.
An SPF record is built using SPF syntaxes (these are of 3 types-mechanisms, modifiers, and qualifiers) that basically carry information about all the IP addresses (ipv4 and ipv6) and mail servers that you allow to send emails on behalf of your company along with instructions for recipients mailboxes on how to treat illegitimate emails coming from your domain.
When these syntaxes or senders’ IP addresses are not laid down correctly, a ‘failed SPF check’ occurs, which completely invalidates your SPF records.
So, to check if your SPF record has any errors, you run it through an online SPF record checker. An SPF record checker (also known as an SPF validator) is a tool that diagnoses your TXT SPF record and highlights errors if found. Some tools also suggest remediation methods so that you fix them timely.
Common Errors Causing an Invalid SPF Record
An SPF validation gets failed due to a number of reasons-
- Extra spaces before or after strings.
- Use of uppercase letters.
- Unnecessary dashes, commas, or spaces between mechanisms.
- Not specifying the type of TXT record in the beginning.
The SPF email authentication process doesn’t work in case of SPF errors. This issue also affects DKIM and DMARC processing, which impacts online marketing due to a low email delivery rate and exposes email-sending domains of reputed organizations to email spoofing.
Main Reasons for SPF Validation Error in Office 365 and Other Platforms
Ensure your SPF TXT records are devoid of these-
Presence of Multiple SPF Records
There can only be one SPF record per domain. If multiple SPF records exist, all of them become invalid and cause failure.
SPF Validation Unavailable
This error indicates that no SPF record for your domain exists on the DNS.
Exceeding the DNS Lookup Limit
A limit of a maximum of 10 DNS lookups is implied to avoid overburdening resources. Staying within this limit is challenging and causes an SPF permerror, but AutoSPF’s SPF flattening service can save you.
This is one of the common problems causing SPF validation errors for Office 365 users. All SPF records must begin with v=SPF1 and end with the ‘all’ tag. The ‘-all’ tag specifies a fail (or hardfail), and ‘~all’ denotes a softfail.
Inclusion of ptr or mx Mechanisms
Their usage should be ignored as they are unreliable and deprecated.
Microsoft Exchange SPF check Error
It’s common for any Microsoft Office 365 host to encounter an email deliverability issue for an important message. Primary factors leading to this are-
Improper Modification of an SPF Record
Domain owners make alterations in SPF records as per shifts in their IP addresses, mail servers, email security preferences, etc. It’s a good practice to keep your TXT records in accordance with these movements to avoid having the ‘SPF validation failed’ status. However, at times, these modifications aren’t done by following the right steps.
Erroneous Configuration of a Spam Filter
Spam filters are tools that process incoming emails to avert any spam message from reaching your inbox. Sometimes, a recipient sets their spam filter on the wrong configuration, which may cause their mailbox to misjudge a legitimate mail server as malicious.
If you have already run your SPF record through an SPF lookup tool and the result says it’s valid, then the most probable reason is some trouble in your domain’s DNS; for example- misconfigured settings, a temporary server outage, or DNS timeout.
DKIM breaks due to relaying and forwarding, which causes SPF and DMARC errors.
SPF Check Failed Gmail
Gmail by Google is one of the most used mailbox providers. Failed SPF checks in Gmail are indicated by the ‘550 SPF Check Failed’ error message and are caused when your recipient server fails to validate the sender’s identity. It may also occur due to relaying of messages through source intermediaries.
How to Fix SPF Validation Error?
Now that you know what all leads to a failed SPF check, let’s see ways to fix it:
Rectify your SPF Records
First, run your records through testers and fix all the highlighted errors. Apart from syntax and configuration mistakes, make sure there are no typos, uppercase letters, and unnecessary dashes, spaces, and commas.
Ensure that the MX Mechanism Points to the Correct Server
SPF validation fails when an SMTP server receives email messages with invalid MX records. So, always verify that your MX record indicates the correct server.
Don’t Skip Adding Forwarders and Third-Party Vendors’ IP Addresses
If a third-party sends mails on your behalf, you must add their IP address to your SPF DNS record. Also, ensure listing those of forwarders too; otherwise, SPF would break, and your email security would be jeopardized.
People Also Ask
What Happens if SPF Check Fails?
When an SPF authentication check fails, your SPF record becomes invalid, and the authentication process stops. This hampers email deliverability and allows threat actors to misuse your domain name for phishing and spoofing.
What Does SPF Authentication Failed Mean?
In simpler terms, SPF authentication failed means that your domain’s SPF record doesn’t include that particular sending email server. This indicates that the sender isn’t authorized to send emails on behalf of your company.
What Causes SPF Fail?
SPF fails when a recipient’s MTA cannot locate a published SPF record in your DNS, or multiple records exist for your domain. It can also happen due to changes in IP addresses or mail servers initially included in your SPF TXT record.
How do I Fix SPF Validation Error?
Check syntax mistakes and misconfigurations, along with ensuring that there are no typos, uppercase letters, and unnecessary dashes, spaces, and commas. See if your MX record indicates the correct server and you’ve added the IP addresses of forwarders and third-party vendors.