SPF record syntax

The SPF record syntax is the format or structure used to write SPF records in your DNS settings. It starts with v=spf1 and then includes a list of rules, like IP addresses or domains that are allowed to send emails on your behalf. Each part of the record must follow certain rules so email servers can read and understand it. A mistake in the syntax can make the record invalid. So it’s important to follow the format exactly.

SPF syntax

SPF syntax is like the grammar of SPF records. It defines how to use different mechanisms like ‘ip4,’ ‘a,’ ‘mx,’ ‘include,’ and qualifiers like +, -, ~, or ?. These parts work together to tell mail servers who can send emails from your domain. If the syntax is wrong, your SPF record might not work properly. Think of it like giving directions—if the grammar is off, people might get lost.

SPF record format

The SPF record format tells you the order and structure of everything inside an SPF record. It always starts with v=spf1 and then lists the allowed senders, ending with something like ‘-all’ or ‘~all.’ The format is important because email providers use it to check if your emails are legit.

SPF record ‘all’

The ‘all’ part in an SPF record sets the final rule for all other senders not already listed. It’s usually written at the end, like ‘-all,’ ‘~all,’ or ‘?all.’ It tells mail servers what to do if an email doesn’t match any of the approved senders. For example, -all means reject the email, while ~all means softfail (treat it suspiciously). Choosing the right one depends on how strict you want to be.

SPF ipv4

ip4 is a mechanism used in SPF records to allow a specific IPv4 address to send email from your domain. For example, ip4:192.0.2.1 means this IP is trusted to send emails for you. If you use email hosting or a third-party sender, their server’s IP should be added using ip4. You can also specify a range of IPs. This is useful if your service provider uses multiple IPs to send emails.

SPF ‘all’ syntax

The ‘all’ syntax tells mail servers what to do with any emails not matching earlier rules. It’s written with a qualifier like -all, ‘~all,’ ‘?all,’ or ‘+all.’ ‘-all’ is the strictest, telling servers to reject unmatched emails. ‘~all’ is softer and usually used during setup or testing. 

SPF a:

The a: mechanism checks if the domain’s A record (its main IP address) is allowed to send emails. For example, a:example.com means emails coming from the server listed in example.com’s DNS are okay. You can use it when your website server also sends email. If no domain is written (just a), it refers to your own domain. It’s a quick way to authorize a domain’s main server.

SPF a

When you use just ‘a’ in your SPF record, it means the A record (IP address) of your domain is allowed to send emails. If your email and website use the same server, this is helpful. But if you use another provider to send email, you’ll need to add their IP too. Keep in mind, the ‘a’ mechanism might not be enough on its own.

SPF ip4

ip4 is one of the most common parts of an SPF record. It allows specific IPv4 addresses to send emails from your domain. You can add one IP like ip4:203.0.113.5, or a whole block like ip4:203.0.113.0/24. This tells email servers that these addresses are safe. Always use the IPs given by your email provider.

SPF include

The include mechanism lets you trust another domain’s SPF settings. For example, if you use Google Workspace, you’ll add ‘include:_spf.google.com’ to your SPF record. This informs email servers that Google’s IPs are authorized to send emails on your behalf. It’s helpful when you’re using third-party services. Just be careful not to include too many domains, or your SPF record could get too long.

SPF record include

This simply means that you are adding some other domain’s SPF rules into your own. For example, include:_spf.mailprovider.com allows that mail provider to send emails on your behalf. It helps when you use services like Google Workspace or Mailchimp. Remember that each instance of the ‘include’ statement is counted towards the DNS lookup limit of 10. So, only use them when required.

SPF ?all

The ?all qualifier in SPF means “neutral,” which means you are not sure if this email is sent by an authorized person or not. So, if an email is sent from an IP address outside of the list mentioned in your SPF record, mail servers won’t reject it, but they won’t fully trust it either.

It’s not recommended to use this mechanism because it doesn’t offer any protection. It’s almost equal to having no SPF for your domain.

SPF mechanisms

Mechanisms are the building blocks of an SPF record. Common ones include ip4, a, mx, include, and all. Each mechanism checks different things, like IP addresses, DNS records, or other domains. They help mail servers figure out who is allowed to send emails from your domain. Think of them like filters or checkpoints.

SPF record options

These are the different choices you have when writing your SPF record. Options include mechanisms (like ip4, a, include) and qualifiers (like -, ~, ?). Together, these options define how strict or relaxed your policy is. 

SPF ‘include’ IP

This term usually confuses people. You don’t directly include an IP with the include mechanism; you include another domain’s SPF record, which may contain IPs. For example, include:_spf.provider.com means you trust all the IPs listed in that provider’s SPF record. If you want to add a specific IP yourself, use ip4: or ip6: instead. 

sample SPF records

Sample SPF records are examples that show you how a real SPF record looks. One simple example is:

v=spf1 ip4:192.0.2.0/24 include:_spf.google.com ~all

This line allows emails from a specific IP range and Google, while marking everything else as softfail. Samples are useful when you’re writing your own record for the first time. Just make sure to customize them for your actual email setup.

SPF format

The SPF format refers to how the entire SPF record is written in a single line. It starts with v=spf1, followed by rules like ip4, a, or include, and ends with all. 

SPF ip4 syntax

The syntax for ip4 is simple: you write ip4: followed by the IP address or range. For example, ip4:203.0.113.5 is one IP, and ip4:203.0.113.0/24 is a range. This tells mail servers that those IPs are allowed to send emails from your domain. 

SPF record ip4

This means your SPF record includes one or more ip4 mechanisms. You’re listing the IP addresses that are allowed to send emails for your domain. For example: v=spf1 ip4:198.51.100.23 -all. Adding these helps email servers trust your outgoing emails.

SPF options

SPF options mean different ways to set up your SPF record. You have the choice to add whichever domains, IPs, or email providers you want. Then you can add the right set of mechanisms and modifiers like ip4, a, include, and ‘all’ to tighten your SPF record.

Add IP to the SPF record

It simply means adding new IP addresses to a pre-existing SPF record so that emails sent from it are not rejected or marked as spam.

SPF ‘include’ vs ‘a’

‘include’ and ‘a’ do two different things in SPF. ‘include’ pulls in another domain’s SPF record so you can trust all the IPs they use. ‘a’ checks your domain’s own server IP. For example, include:_spf.google.com allows Google’s mail servers, while ‘a’ allows your website’s server.

SPF ~all vs -all

~all means ‘softfail,’ which essentially instructs the receiving mail servers to place the suspicious emails in the spam folder. -all means a ‘hardfail,’ and this instructs the receiving mail servers to reject the emails that are not sent from IP addresses authorized by you.

SPF record meaning

An SPF record is a rule you add to your domain’s DNS to tell mail servers who’s allowed to send email for you. It helps prevent scammers from faking your email address. Without it, anyone could send an email pretending to be you.

SPF record types

As of now, there is only one official SPF record type, and that is ‘TXT record.’ It is published in your domain’s DNS. Earlier, there was an SPF-specific DNS type, but that is obsolete now for various technical reasons. 

SPF ‘include’ statement

The ‘include’ statement is used when you want to add some other domain’s SPF record to yours. This way, you don’t have to enlist all the same IPs manually. Remember not to use too many ‘include’ statements, as it can break your SPF record.

SPF record mx

The mx mechanism allows the mail servers listed in your domain’s MX records to send emails for you. If you use your own domain’s mail servers, adding mx makes sense. For example: v=spf1 mx -all means “allow my MX servers and block everything else.”

SPF exists

The ‘exists’ mechanism helps check if a specific domain exists in DNS. If it does, the rule passes, and the sender is approved. The ‘exists’ mechanism is rarely used, but it is helpful for advanced, complicated SPF records.

SPF record ‘mx’

This just means your SPF record contains the mx rule. It allows emails from the mail servers listed in your MX records. For example: v=spf1 mx include:_spf.provider.com -all allows both your MX servers and your provider’s.

SPF policy

Your SPF policy is the rule you set for who can send email from your domain. It’s everything inside your SPF record. The policy could be strict (block unknown senders) or loose (just mark them). The final ‘all’ rule decides the strictness.

Define SPF

SPF is short for Sender Policy Framework. It’s an email authentication protocol that lets you instruct the mail servers which senders are allowed to send emails from your domain.

SPF ip range

Instead of adding one IP, you can allow a whole range using CIDR notation. Example: ip4:203.0.113.0/24 covers all IPs from 203.0.113.0 to 203.0.113.255. This is useful if your provider uses multiple IPs to send emails.

SPF codes

SPF results come with codes like “pass,” “fail,” “softfail,” or “neutral.” They tell the receiving server what happened when checking your SPF record. For example, “pass” means the sender was approved. 

SPF fail not authorized

This happens when an email comes from a server not listed in your SPF record and your policy says to reject it (-all). The receiving server will treat it as “fail” and may block it completely. It’s a sign someone might be spoofing your email.