Overview
When Element451 sends email on your behalf—such as notifications, marketing campaigns, or transactional messages—those messages are delivered through dedicated sending IP addresses. These IPs help ensure reliable delivery and maintain a strong sender reputation for your institution.
Because colleges and universities often use stricter email filtering rules than consumer providers like Gmail, Yahoo, or Outlook.com, trusted vendor traffic may be blocked unless it’s explicitly allowed. To ensure faculty, staff, and students consistently receive important messages from Element451, we strongly recommend adding our sending IP addresses to your institution’s allowed lists.
Why Do We Share Our IP Addresses?
Whitelisting: If your organization’s email filters or firewalls are strict, you might need to “whitelist” (approve) specific IP addresses so that emails from Element451 aren’t blocked or marked as spam.
Email Delivery Assurance: By knowing our IP addresses, you can more easily troubleshoot any issues with email delivery or filtering.
Current IP Addresses
We currently use the following IP addresses, each dedicated to specific email types:
149.72.207.3 – Conversations, Transactional Emails
149.72.212.156 – Marketing Emails
149.72.223.121 – System Emails
149.72.130.92 – Backup
149.72.24.235 – Backup
We may add or update these IPs in the future as we grow or adjust our email-sending infrastructure. Check back here for the latest information.
Do I Need to Do Anything?
If your organization uses strict filters, we recommend having your IT team whitelist the IPs listed above to ensure smooth email delivery. However, if you’re already receiving our emails without any issues, there’s likely nothing you need to do. Should you encounter any problems, please contact our support team or collaborate with your IT department to confirm that these IPs are allowed in your environment.
Security and Reliability
Reputation & Monitoring: We use a reputable email service provider (SendGrid) that actively monitors IP health and blocks malicious activity.
Encryption & Authentication: Our emails use standard protocols like SPF, DKIM, and DMARC to verify senders and protect against spoofing.
Ongoing Maintenance: We regularly review the performance of our email-sending IP addresses. If we ever need to replace or add IPs, we’ll update this list.
Special Considerations for Microsoft Exchange Online
Some institutions use Microsoft Exchange Online (Office 365) to receive email. Exchange Online applies multiple layers of filtering and policy enforcement that can sometimes reject legitimate, system-generated email even when sending IPs are whitelisted. In this case, we recommend also configuring an Inbound Connector in additionl to standard allow-list (whitelisting).
This behavior is specific to Exchange Online and does not typically apply to:
On-premises Microsoft Exchange servers
Google Workspace (Gmail)
Other third-party mail gateways or providers
Why this happens in Exchange Online
Why this happens in Exchange Online
Exchange Online evaluates incoming mail using several stages, including connection filtering, policy enforcement, and mail flow rules. While IP allow-listing is often sufficient to bypass spam filtering, tenant-level policy rules may still reject messages at an earlier stage.
When this occurs, Exchange Online may return an error similar to:
550 5.4.1 Recipient address rejected: Access denied
This can happen even if:
The sending IP is allow-listed
SPF, DKIM, and DMARC are configured correctly
Previous messages from the same IP were delivered successfully
Because this rejection occurs at the policy or transport layer, delivery can appear inconsistent without additional configuration.
Recommended configuration for Exchange Online tenants
Recommended configuration for Exchange Online tenants
To ensure consistent delivery from Element451, Exchange Online administrators may need to configure both of the following:
IP Allow-Listing
Add all Element451 sending IP addresses (listed above) to your connection filter allow-list.Inbound Connector (Exchange Online only)
Configure an Inbound Connector using the same IP list. An inbound connector explicitly tells Exchange Online to trust email originating from these IPs and helps prevent policy-level rejections that simple allow-listing may not override.
Inbound connectors are commonly used in higher-education environments for trusted vendor platforms that send automated or system-generated email, such as CRMs, admissions systems, and LMS integrations.
Important notes
Inbound connectors are specific to Microsoft Exchange Online (Office 365)
They are not required for on-prem Exchange or most other email platforms
Inbound connectors do not bypass malware scanning or authentication enforcement; they simply prevent tenant-level access denials
Questions or Concerns?
If you have any questions about these IP addresses or how Element451 sends emails, contact our support team. We’re here to help you set up or troubleshoot your email environment.