Limit Spoofing and Phishing Attacks with a Reliable SPF Record Intact

Author
Dariia Leshchenko
Published
Apr 28, 2022
Reading duration
7m

Spreading the word about your unique products and services over email is one of the most fruitful ventures to extend your user base, grow revenue, and polish vendor reputation. However, there are countless cases where the domain name of a reputable brand is compromised by spoofing and phishing attacks. Would you like to ensure that your email messages are safely delivered to the recipient with no harmful alterations enforced? It is time to disclose the perks that a reliable SPF record offers. Folderly experts are willing to share the secrets that others may not want you to know!

What are email spoofing and phishing?

Before you get to know what SPF record stands for and what it is supposed to do, you may want to start with a simple definition of email spoofing and phishing to learn what you are fighting against.

Spoofing is a fraudulent activity that is aimed at the email header. The end result of this is third-party email messages that seem to be sent from a trustworthy brand or domain. But in real life, the primary goal of such messages is to steal the receiver’s sensitive data and use it for scamming purposes.

Phishing messages work similarly. Usually, a user receives a warning email that indicates a security breach. To deal with the so-called breach, the email says the person should follow the link attached and provide the requested personal data. The phishers will later exploit the shared information to hack into banking accounts or even individual devices to steal money or valuable data. There are cases when access to your computer is blocked due to such a phishing attack so that a ransom is requested to restore your access to the device.

To sum up, spoofing is a type of fraudulent impersonation that results in stolen data and loss.

Can you prevent spoofing and phishing?

Is it possible to ensure messages that come from you are safe and secure? As a matter of fact, there is nothing complicated about how to prevent spoofing. It takes proper email authentication to keep the incoming spam at bay. There are three main protocols responsible for proper email authentication. They are SPF record, DKIM, and DMARC.

DMARC, SPF, and DKIM protocols are designed to provide particular DNS records, which ensure that a domain in use is secure and reliable. When combined with the safety measures that most ESPs have intact, the implementation of SPF records and other protocols will keep spoofing attempts at bay.

The basic definition of SPF record

The Sender Policy Framework is the basic definition of an SPF record. The primary role of the record is to ensure email reliability and prevent spoofing so that receiving servers and user inboxes, as a sequence, keep clear of spam messages. SPF records usually contain the list of IP addresses related to the sending domain and have the right to send email on behalf of the owner.

Receiving servers are programmed to detect messages sent from separate domains. After such an email is sent, the servers will check if the SPF record is intact. Should the IP that the sender is related to be on the list of whitelisted IP addresses, your email will be delivered. Once the mail server detects something unusual about the email, it will be rejected.

SPF record and email servers

The key step to take to prevent spoofing is to make sure that when you send mail, all the messages are authenticated. Thus, SPF protocol as the standard of practical DNS records should be used to predefine all the mail servers enabled to send email from your domain. So, the primary step against spoofing is to declare the servers.

Every time a message is issued from your company to another, the receiving servers will inspect if the email comes from the legitimate domain. All the incoming messages will be sent to spam if the sending domain is listed as an unauthorized one.

There are cases when the domain is reliable and verified, but an error occurs during the configuration stage of presetting an SPF record. Once an SPF record misconfiguration occurs, it will result in delivery problems. So, it is best to stick to the guide provided by the ESP in use as to the settings required.

A visual example of SPF record to note

SPF record syntax may seem like a complicated notion that not everyone is trained to grasp. However, as long as you are aware of the main components of the record’s syntax, you will be able to spot a mistake should one occur.

Here is a classic example of SPF record:

v=spf1 ip4=192.0.2.0 ip4=192.0.2.1 include:testrecord.email -all

v=spf1 – the entry is used to inform the servers that the TXT record in use is an SPF record. Each SPF record starts with the mentioned string. No exceptions are known.

ip4 – the string indicates the number of IP addresses authorized to send email messages from a domain. Every IP is mentioned as a TXT record.

include:testrecord.com – the include tag carries out the mission of notifying the servers about who can send email from your domain. Such tags verify that the content of the SPF record, along with the IPs added to the list, are authorized. Keep in mind that more than one domain can be implemented with a valid SPF record.

-all – the entry is used to verify that only the addresses added to the SPF record count as authorized and that the rest aren’t enabled to be sending emails on your behalf. However, that is not the only type of string that may occur. There are two more:

  • ~all
  • +all

In the ~all case, the entry means that if there are any unlisted addresses that come from the domain, they will be marked as spam but will be delivered. +all tag means that all mail servers can send emails from the domain in use. However, such occurrences are extremely rare.

Are there any SPF record limits?

All the TXT records have a role to play when it comes to sending emails and delivering trusted messages to the recipients. However, not only do DKIM and DMARC records prove to be anything but omnipotent, but SPF records do too. You need to keep a few limitations connected to spoofing in mind.

SPF record can’t be applied to the From address

In case you don’t know, there is more than one address to identify the sender. There are From addresses and Return-Path addresses to distinguish between. The latter one is usually hidden. Once you enable your SPF record, the receiving servers will pay attention to the hidden address and check the SPF related to the domain that is connected with the Return-Path address.

Since we are talking about spoofing today, it needs to be mentioned that hackers can apply a fraudulent detour to confuse the SPF TXT record. They can exploit a fake domain in the Return-Path address and a legitimate one in the From address section. Such an approach ensures that the recipient will see a legitimate sender in the From section and won’t consider similar messages as spam.

SPF record and DNS lookup limit

SPF TXT record is provided with the list of IP addresses approved by the domain, and receiving servers have the task of checking them out to figure out which sender is authorized. In order to decrease the server load, there is a 10 DNS lookups limit induced by SPF records.

Such an approach means that if your company cooperates with more than one third-party vendor that uses your domain, the SPF record will inevitably exceed the mentioned limit. Should that happen, the SPF in use will be considered invalid, and that will lead to delivery rates dropping. It takes proper SPF optimization to escape this unfavorable outcome, and you would need to hire skilled professionals to help you do that.

SPF TXT records and Forwarded messages

To put it simply, Forwarded emails don’t work well with SPF records. If you have an SPF TXT record encoded with your domain and someone chooses to forward your message, it will be rejected due to the existing SPF policy. The failure can affect your deliverability rates negatively, so it is best to keep away from the forwarding practice.

Final words

SPF record implementation is one of the best ways to ensure that neither your address nor your domain will be used for spoofing. It takes time and effort to master the SPF policy, and there are expected drawbacks to think about. However, the digital security of your users has a direct impact on the success of every venture and campaign that your company undertakes.

Dariia Leshchenko
Author:
Dariia Leshchenko
Customer Success Manager
Dariia's decades in Email Deliverability and Sales have allowed her to successfully manage diverse business clients. For years now, she proves that there are no issues not to be fixed. Dariia speaks for the synergy of new-level email analysis technology and a human approach to improving email performance.