Sender Policy Framework (SPF) is a protocol used to prevent spammers from sending emails with forged ‘From’ addresses at your domain.
An SPF record is a type of TXT record that identifies any mail servers permitted to send emails on behalf of your domain; they are also known as Reverse MX records.
Domain administrators publish SPF records in the Domain Name System (DNS); this enables the incoming mail servers to verify the domain name from which emails are sent. When a recipient's mail server receives an email, it checks the SPF record to determine whether it is a valid email. If the email comes from a server that is included in the SPF record, it is legitimate; if not, it is rejected as spam.
Do I need to update the SPF records?
Yes, we recommend that you update the SPF records to include the Exclaimer SPF record. This will ensure that emails that have been transported through our system are not identified as suspicious and blocked by the recipient.
How do I update the SPF records?
The exact process varies from one service provider to another; generally, it involves adding one line to a DNS TXT record.
You, as an IT Administrator, need to update the SPF records based on the Exclaimer Simple Mail Transfer Protocol (SMTP) hosts.
UK United Kingdom
US United States
NOTE: For more information, see How to update the Sender Policy Framework (SPF) record.
Can I have multiple SPF records?
Multiple SPF records are not recommended as this can cause issues with delivery and/or spam classification.
Domain Name System (DNS), is a system that is used to identify and organise Web domains.
It is similar to a telephone directory for the Web, which allows network communication services to look up names and translate them into Internet Protocol (IP) addresses.
DNS information is gathered from all domain name servers across the Internet and stored at the Central Registry. Hosting companies and Internet Service providers interact with this registry on a regular basis to obtain the updated DNS information.
So, when you type 'www.exclaimer.net' into a web browser, DNS looks up for this address and establishes which IP address should be used to make a connection then it displays the web page.
For emails, it's a little bit complicated if you start to look at how an email is sent and received. We'll have to dig deep and look at DNS records. Although DNS includes different types of records for specific purposes, for this article, we are discussing two particular types of records: mail exchanger (MX) and text (TXT).
- mail exchanger record (MX) are resource records within the DNS that specify a mail server responsible for accepting email messages on behalf of the recipient's domain, together with a preference value which is used to prioritize delivery if multiple mail servers are available. All domains publish MX records so we know which servers can receive email for the domain. So, when an email is sent, the sending mail server looks up for the MX record in the DNS to obtain the relevant IP address.
- text record (TXT) is a DNS record that provides text information to sources outside your domain; it can be used for many different purposes, one of which is Sender Policy Framework (SPF). So when we refer to SPF records, we are referring to a particular type of TXT record within the DNS.