When you’re selecting your approach to email security, your decision isn’t just about security—it’s about how your organisation operates. Does your team prioritise speed and agility, or is reducing risk your top priority? Do you exclusively rely on native email security, or do you prefer a diversified security stack? Is your email infrastructure simple, or does it require complex routing and customisation?
The answers to these questions will help you work out whether you need API-based email security or a secure email gateway (SEG). Each approach has distinct advantages. And if you make the wrong choice, it can lead to inefficiencies, increased costs and security gaps.
Here, we’ll break down the three key factors that should drive your decision.
1: Fast execution vs strategic risk management
Some organisations want a solution that’s quick and easy to deploy, delivering immediate value. Others want robust, multilayered defences—and they don’t care if deploying it takes a while. Where your organisation stands will help you determine the right model.
When to choose API
If your organisation values speed and efficiency, then an API-based deployment is the ideal choice. API email security can be up and running in days. And automated protection can kick in 48 hours after historical user data is analysed. This approach is well-suited for companies that:
- Have lean security teams with no time for custom configurations
- Prefer automated security that adapts dynamically to new threats
- Want seamless deployment without disrupting existing email flows
Security teams wanting to deploy protection without modifying mail routing (which may fall under IT or messaging teams) often prefer API-based deployments. An API approach enables fast, effective protection without major infrastructure changes.
When to choose SEG
If your organisation leans toward strategic risk management, an SEG is the better fit. While they do take weeks rather than days to deploy, they provide multiple layers of security. You can expect:
- Pre-delivery filtering to block malicious emails before they hit inboxes
- Post-delivery threat detection for added resilience against evolving threats
- Click-time protection to stop users from making costly mistakes
SEGs are often preferred by dedicated security teams needing full control over their email environment. That’s because SEGs have extensive policy configuration options. While the trade-off is a longer deployment timeline, the increased visibility and control over email threats can significantly reduce risk.
The cost of making the wrong choice
- Choosing API when you need SEG. If you opt for API-based security and you have complex security needs, then you may miss out on the configuration and customisation options that are needed by your organisation.
- Choosing SEG when you need API. If your organisation needs a solution that’s up and running in just days, an SEG might slow down implementation.
2: Microsoft orientation: partner or exclusive provider?
How you’re aligned with Microsoft will determine whether API-based security or an SEG is the better fit. Some organisations are fully committed to Microsoft and want to enhance its built-in security. Others want a standalone security product that operates independently.
When to choose API
If you’re all-in on Microsoft, then an API-based approach works well. API-based solutions can augment Microsoft’s native protections without disrupting workflows. With a Graph API integration, these solutions can:
- Work natively within Microsoft 365, ensuring seamless user experience
- Provide enhanced threat detection beyond Microsoft’s built-in protections
- Provide users with a native Outlook experience for managing spam and graymail
Messaging teams (responsible for MX records and mail routing) may prefer API-based solutions because they don’t require email to be rerouted through an external SEG. And security teams (focused on detection and threat response) benefit from the additional protection layers provided by API-based tools, which enhance Microsoft’s existing security.
When to choose SEG
If your organisation needs a more strategic approach to stop email threats, an SEG is the better choice. It will:
- Deploy ahead of Microsoft’s SEG and provide pre-delivery protection
- Add post-delivery protection for threats that are weaponised after they reach user inboxes
- Offer users a dedicated browser isolation experience for click-time protection
An SEG is best for organisations wanting a solution that adds several layers of protection to Microsoft for added redundancy and resilience.
The cost of making the wrong choice
- Choosing API when you need SEG. If your team wants pre-delivery protection, an API-based solution will likely mean that higher volumes of email threats will reach your users’ inboxes.
- Choosing SEG when you need API. If your team is fully committed to Microsoft, an SEG may disrupt existing workflows and require additional policy management and user training.
3: Email infrastructure: simple vs sophisticated
How your email is routed, filtered and managed should heavily influence your choice. Some organisations have a straightforward email flow. Others, meanwhile, have complex, customised infrastructures requiring more options for their teams to configure.
When to choose API
If your email setup is simple, then an API-based solution provides seamless protection. And it has minimal overhead. This is especially true if:
- Your organisation uses Microsoft for mail routing and doesn’t require additional configurability.
- You have a single-domain environment with straightforward email policies.
- You prefer automated threat detection without managing policies.
For example, companies with a centralised IT team often find that API-based security meets their needs.
When to choose SEG
If your email infrastructure is more sophisticated, then an SEG is the right fit. SEG deployments provide:
- Granular routing that’s based on sender domain, authentication status and more
- Advanced filtering logic that adapts to complex business needs
- Customisable threat response workflows that integrate with security operations
For example, companies with multiple email environments, complex routing policies or regulatory compliance needs often require the precision and control that an SEG provides.
The cost of making the wrong choice
- Choosing API when you need SEG. If your infrastructure requires customised routing and filtering, an API solution may lack the control you need. This will force your security teams to work around its limitations.
- Choosing SEG when you need API. If your infrastructure is simple, deploying an SEG may add unnecessary complexity. This will lead to wasted resources and slower response times.
Making the right choice for your organisation
When you’re choosing between SEG and API-based email security, you shouldn’t ask which one is better. Instead, you should ask which option best aligns with your priorities, your Microsoft integration and your infrastructure needs.
Comparing API-based security with SEGs.
No matter which option you choose, getting email security right is critical. An informed decision ensures that your security teams can operate efficiently, your employees stay protected and your organisation avoids costly breaches.
Protect your people with Proofpoint
Proofpoint Core Email Protection stops 99.99% of email threats before they become compromises. It uses industry-leading detection and automated remediation to block advanced threats, such as business email compromise (BEC), ransomware and phishing.
Offered as an SEG or API, Proofpoint Core Email Protection can be deployed to suit the needs of any customer
You can choose the Proofpoint deployment method that best suits your organisation. We offer options for both SEG and API-based deployments. Learn more by downloading our Core Email Protection solution brief. Or visit our webpage.
