This guide will show you how to allow-list usecure's IP addresses in the following Mimecast policies:
Anti-Spoofing Policy
Spoofing involves manipulating email headers to make it seem like a message is coming from a different sender. This method is commonly used in phishing and spam attacks, as people are more likely to open emails that appear authentic. Anti-Spoofing measures help block emails that seem to originate from an internal domain but are actually from external sources.
Follow the steps below to allow usecure to send emails appearing to come from an email address at your domain on your behalf.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select Anti-Spoofing from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring an Anti-Spoofing Policy article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Permitted Senders Policy
Permitted Senders policies ensure that inbound messages from trusted sources are delivered successfully. Emails from these senders bypass Reputation, Greylisting, and Spam Scanning checks, preventing them from being rejected or placed in a Held queue. This is especially helpful when the sender's messages are flagged by Mimecast's security filters.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies
Select Permitted Senders from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring a Permitted Senders Policy article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Attachment Protection Bypass Policy
To ensure that emails with attachments in your simulated phishing tests reach your users' inboxes, follow the steps below to improve delivery success.
Note: Mimecast may still prevent the delivery of attachments.
Set up a test after creating this policy to ensure that attachments are being delivered.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select Attachment Protection Bypass from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring Attachment Protection Bypass Policies article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
URL Protection Bypass Policy
Mimecast's URL Protection Service scans and checks the URL links in emails upon delivery. This can sometimes result in false positives for your phishing security tests.
Follow the steps below to create a URL Protection Bypass policy for accurate phishing security test results.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select URL Protection Bypass from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring a URL Protection Bypass Policy article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Impersonation Protection Bypass Policy
If you’re sending phishing emails, appearing to come from domains from your organisation, you'll want to create an Impersonation Protection Policy in your Mimecast admin console.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select Impersonation Protection Bypass from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring an Impersonation Protection Bypass Policy article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Attachment Management Bypass Policy
If you'd like to use attachments in your simulated phishing tests, follow the steps below to prevent attachments from being stripped from emails, potentially resulting in skewed test results.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select Attachment Management Bypass from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring Attachment Management Bypass Policies article.
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Greylisting Bypass Policy
You may want to set up this policy if you want to stop Mimecast from preventing emails being deferred. Below are instructions on how to add this policy.
Log on to your Mimecast Administration Console.
Navigate to Gateway > Policies.
Select Greylisting from the list of policies displayed.
Click on New Policy.
Select the appropriate policy settings under the Options, Emails From, Emails To, and Validity sections.
For more information on these settings, see Mimecast's Configuring Greylisting Policies article. (Opens in a new window.)
In the 'Source IP Ranges' field, enter our IP ranges shown here.
Click Save and Exit.
Next steps
Find out how to allow list by IP address in Google Workspace
Find out how to allow list by IP address in Office 365