Adding Arsen’s sending domains to the Safe Sender List ensures that Outlook correctly displays embedded images in HTML phishing scenarios and prevents internal policies from altering simulation emails.
This guarantees a realistic and effective training experience.
1 – Objectives
Ensure correct display of embedded images in HTML scenarios.
Prevent Outlook from altering or modifying simulation emails.
Automatically add Arsen domains to the Safe Sender List of all user mailboxes.
Enable more realistic and representative phishing training.
2 – Prerequisites
2.1 - Compatible licenses
One of the following licenses is required:
Exchange Online Protection
Microsoft Defender for Office 365 Plan 1 or Plan 2
Microsoft Defender XDR
2.2 - Supported environments
This procedure applies to:
Exchange Server 2010
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
Exchange Online
Exchange Online Protection
2.3 - Useful Microsoft documentation
Create safe sender lists in EOP
Set-MailboxJunkEmailConfiguration
Get-Mailbox
3 – Add Arsen Domains to the Safe Sender List
This PowerShell command works for both Exchange on-premises and Exchange Online.
(Note: some parameters may vary by environment.)
3.1 – Command to execute
$All = Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited $All | foreach {Set-MailboxJunkEmailConfiguration $_.Name -TrustedSendersAndDomains @{Add="[DOMAIN_1]","[DOMAIN_2]","[DOMAIN_X]"}}Replace:
[DOMAIN_1], [DOMAIN_2], [DOMAIN_X] with the Arsen sending domains you want to authorize.
Up to 1000 domains can be added.
3.2 – Adjust the $All variable
Depending on your needs, you can limit the command to:
specific groups
specific Organizational Units
selected mailboxes
3.3 – Verify the configuration
After running the command:
Sign in to a targeted user account. (link referenced as “Learn more”)
Go to Outlook → View → View settings → Junk email.
Check that the Arsen domains appear in the Safe Senders list.
3.4 – Retrieve the full list of Arsen domains
In Arsen:
Open the
Phishing Simulation Settings.Follow the whitelisting procedure up to the final step.
Copy/paste all Arsen domains available there.
4 – Remove Arsen Domains from the Safe Sender List
To remove previously added domains, run the same command but replace Add with Remove:
$All = Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited
$All | foreach { Set-MailboxJunkEmailConfiguration $_.Name -TrustedSendersAndDomains @{Remove="[DOMAIN_1]","[DOMAIN_2]","[DOMAIN_X]"}}