How to add CybSafe to your allow list

For the best experience, you may have to add allow list rules to your organisations systems

Jonathan Webster avatar
Written by Jonathan Webster
Updated over a week ago

We recommend forwarding this article to IT administrators responsible for mailboxes and gateways (e.g. Azure & Mimecast), and internet traffic gateways.

Allow list for browser and app is the fully qualified domain name in use.

Other external URLs in use:

Allow list for receiving emails

For mail servers and mail gateways

Please note: While you can allowlist based on sender domain, we highly recommend you allowlist based on IP address.

To make sure our emails reach people, you need to arrange for the following IP addresses and domains to be allow listed in your mail servers:

For more information around this, please click here.

  • Registration, News and Administration – IP /

Both these IP addresses are dedicated to CybSafe.

If you are using a mail filter, both your email solution and inbound gateway (Filter) need to use allow list rules be allowlisted

Additional IP addresses for simulated phishing attacks

CybSafe can also send out phishing emails from an expanded range of IP addresses. We recommend that you allowlist all the following IP addresses to ensure you do not experience throttling or having our emails blocked from one address.





Allowing phishing emails to be sent from multiple domains from CybSafe

Once you have allowlisted the four additional phishing IP addresses, you will be able to receive CybSafe phishing emails from an expanded range of domains. If you have allowlisted only our default IP address, all phishing emails will be sent from

After allowlisting, contact [email protected], or your account manager if you have one, and ask them to enable expanded phishing domains. Your phishing campaigns will then start to send emails from more domains.

Please note: Enabling additional domains will change the DKIM signature from CybSafe phishing emails from the default em.cs-mail-sender. If you are using the DKIM signature for any other purposes (e.g. triage), we recommend that you do this based on the Message ID of our phishing emails, which will always end in

For Microsoft 365

To allow the training reminders and simulated phishing emails to reach your people, the CybSafe servers must be allow-listed on your mail platform(s). This is usually either Microsoft365 or an on-premise mail server. If you use an external email scanning service (e.g. FireEye ETP, Mimecast, MessageLabs or Proofpoint), you will also need to allow CybSafe emails on their system. Please consult their documentation for details of how to do this.

Note – the domains “” and “” are used in the MailFrom attribute as per RFC 5321, not in the From attribute as defined in RFC 5322. This ensures that even when the “From” address seen in the email does not match – which is the case for phishing emails - the rule will still be applied.

Exchange Online Protection - advanced delivery policy

Exchange Online Protection (EOP) does not allow safe lists or filtering bypass for messages that are identified as malware or high confidence phishing. But, there are specific scenarios that require the delivery of unfiltered messages such as a CybSafe Phishing Campaign.

Follow the steps in this Microsoft article to ensure delivery of our Emails:

Configure the delivery of third-party phishing simulations to users and unfiltered messages to SecOps mailboxes

NB: you will need to add /* to the end of urls added here for Microsoft to process them correctly

Microsoft Defender

If your organisation uses Microsoft Defender, you may need to configure settings in it to allow CybSafe phishing emails to be delivered.


If you're using Mimecast Email Security you can allow list CybSafe to permit our simulated phishing emails and training invitations through to your end users.

In this article, "Additional Allowlisting Information for Mimecast", you’ll find instructions for several different policies, which you’ll need to add to your Mimecast console to allow the use of CybSafe.

Still have any questions?

If you still have questions, you can contact the CybSafe team via [email protected]. We’re on hand to help resolve any further issues!

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