Email spoofing best practices

  • Last updated on: 2017-11-14
  • Authored by: William Loy

This article explains email spoofing and describes the steps that you can take to combat it.


  • Applies to: Administrator and User
  • Difficulty: Moderate
  • Time needed: Approximately 15 minutes
  • Tools required: Email access

For more information on prerequisite terminology, see Cloud Office support terminology.

If you would prefer a video tutorial see Rackspace Email - Spoofing: How to identify & protect your organization.

What is email spoofing?

The word spoof means falsified. A spoofed email is one in which the sender purposely alters parts of the email to make the message appear as though it was authored by someone else. Commonly, the sender’s name and email address and the body of the message are formatted to appear from a legitimate source. Sometimes, the spoofer makes the email appear to come from a private citizen.

A spoofed message can appear to come from a coworker, a bank, a family member, or any number of seemingly trustworthy sources. A good spoof looks like any other email that you normally receive.

Warning: If you suspect that you have received a fraudulent message, DO NOT click any link in the message or enter any information that is requested.

Why do people spoof email?

In many cases, the spoofed email is part of a phishing (scam) attack. In other cases, a spoofed email is used to dishonestly market an online service or sell you a bogus product. The intent is to trick the recipient into making a damaging statement or releasing sensitive information, such as passwords. If you’re receiving bounced (returned) emails for messages that you never sent, this could be a case of spoofing.

Identify a spoofed message

Scammers alter different sections of an email to disguise who is the actual sender of the message. To view the following properties, you must open the email headers of a message that you suspect has been spoofed. Following are some examples of spoofed properties:

  • FROM - This appears to come from a legitimate source on a spoofed message.

  • REPLY-TO - This can also be spoofed, but a lazy scammer might leave the actual REPLY-TO address. If you see a different sending address here, the email might have been spoofed. m
  • RETURN-PATH - This can also be spoofed, but a lazy scammer might leave the actual RETURN-PATH address. If you see a different sending address here, the email might have been spoofed.

  • SOURCE IP address or “X-ORIGIN” address - This is typically more difficult to alter but it is possible.

The first three properties can be easily altered by using settings in your Microsoft Outlook, Gmail, Hotmail, or other email software. The fourth property, IP address, can also be altered, but usually requires more sophisticated user knowledge to make a false IP address convincing.

In the following example, it appears that the recipient has received a message from their office assistant requesting money.

The subject line should alert you immediately. This user should contact their assistant through another form of communication to confirm that they did not send this message. Next, you want to discover who actually sent the message by opening the message headers. It should look similar to the following:

In this message header snippet, we see that the From: field shows the message being sent from “Assistant”<>. However, we can also see that the REPLY-TO: field lists That is a clear example of a spoofed message.

You should blacklist any address that you find in the REPLY-TO, RETURN-PATH, and SOURCE IP field that is not an email address or IP address from which you normally receive mail.

For more information on viewing and understanding email headers, see View and read Rackspace email headers.

Combat spoofing

User education is the first line of defense against these types of attacks. If a user receives a spoofed message, they should perform the following tasks:

Spoofing is possibly the most frustrating abuse issue to deal with, simply because it cannot be stopped. Spoofing is similar to hand-writing many letters, and signing someone else’s name to it. You can imagine how difficult that would be to trace.

The most impactful change you can make as an administrator is to implement SPF, DKIM, and DMARC records in that order. These are DNS records that add extra layers of protection to prevent malicious email from being sent out using your domain name.

  • Sender Policy Framework (SPF) records help recipient mail servers identify unauthorized use of your domain in the form of forgeries (spoofing). Create an SPF record policy first.

    Note: If you send email from other providers on behalf of your domain, be sure to include their sending servers in the same SPF record entry. Do not create multiple SPF records.

  • DomainKeys Identified Mail (DKIM) records assign a digital signature to mail sent from your domain, marking it as authorized mail sent from your domain. If you require instructions to enable DKIM for your Rackspace Cloud Office email, see Enable DKIM in the Cloud Office Control Panel. Creating a DKIM record is the second step in the process.

  • Domain Message Authentication Reporting and Compliance (DMARC) records indicate to recipient mail servers that messages sent from that domain are employing DKIM and SPF sending policies. The recipient mail server then validates the message that you sent by using your DKIM and SPF policies. Creating a DMARC record policy enables you to enforce DKIM and SPF records. This is the last step in the process.

Using record policies protects the integrity of internal emails, as well as the external reputation of your domain. Implementing this protection is a multi-step process that you must carefully follow. For more information, see Create a DMARC policy.


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