This section is mandatory to ensure attack simulation emails can be successfully delivered to your end-users. The following instructions are for Google Workspace (Gmail).
Whitelist OutThink Email Servers
The following IP Addresses must be whitelisted to bypass spam filtering within your organization. OutThink will send attack simulations from these servers.
- If your OutThink tenant is hosted in the EU data center
147.253.222.115199.15.227.83 - If your OutThink tenant is hosted in the US data center
156.70.77.69168.203.49.20 - If your OutThink tenant is hosted in the CA data center
16.52.240.221
3.99.118.87
Your hosting region is determined by your OutThink tenant configuration, not your company’s physical location. If you are unsure which data center your tenant is hosted in, please contact OutThink Support or your Customer Success Manager.
If your organisation employs an endpoint security device or other gateway which processes all incoming email, the origin IP Addresses of OutThink’s mail servers may not be detected. In this case, it is recommended to whitelist all sender email addresses used by OutThink’s Phishing Simulations instead, as detailed here.
For Google Workspace customers, whitelisting can be achieved as follows. Refer to the Google documentation for further details.
- Login to the Google Admin Console via https://admin.google.com/.
- Navigate to Apps > Google Workspace > Gmail in the side menu.
- Select the Spam, Phishing and Malware options.
- In the Email allowlist, enter all IP Addresses listed at the start of this article, separated by a comma.
- Click Save at the bottom of the screen.
Change Log
New IP Addresses – Updated October 2025
The following IP Addresses have been added for future compatibility. If you have not already included these IP Addresses in the whitelisting rules above, please do so.
156.70.77.69168.203.49.20
Banner photo by Markus Spiske
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