Choosing the Best SMTP Providers – Top 5 SMTP Providers Compliance Comparison

When you manage millions of transactional emails or orchestrate extensive marketing campaigns, the nuances of data protection, privacy, and regulatory adherence can make or break your operations. 

This is precisely why you need to hawk over compliance, and set a goal to find a provider that: 

• Safeguards your data 
• Respects user privacy 
• Helps you navigate the labyrinth of GDPR, CCPA, and HIPAA

To help you make an informed decision, I’ll peel back the layers of documentation, from privacy policies and Data Processing Agreements (DPAs) to providers’ infrastructure disclosures and feature sets. My SMTP providers compliance comparison also incorporates: 

• Insights from practical testing
• The visibility of audit logs 
• The flexibility of account roles 
• The accessibility of DPAs and 
• The robustness of data deletion options

SMTP providers compliance comparison: a snapshot

The snapshot gives you an immediate overview of where each provider typically shines and how they initially position themselves regarding compliance. 

Truth be told, all the providers listed here are compliant, so it’s not like you’ll make a mistake and choose a service that would somehow jeopardize the legality of your campaigns. But the serve slightly different businesses needs, and Amazon SES, for example, requires expertise to set up. 

Anyway, the table below provides a high-level overview. Click on the detailed comparison below for the full analysis.

Methodology

My analysis is built on a two-pronged methodology: 

1. Rigorous documentation review 
2. Practical, hands-on testing 

I aimed to make the insights theoretically sound and reflective of real-world functionality for high-volume senders. So, here’s the gist of it. 

Documentation research:

• Privacy policies: To understand how each provider collects, uses, stores, and protects personal data.
• Data Processing Agreements (DPAs): Crucial for GDPR and other privacy regulations, I examined the terms and responsibilities outlined for them as data processors. This included looking for clear commitments on data security, incident response, and sub-processor management.
• Infrastructure disclosures: Understanding where and how their data centers operate, their network security, and redundancy measures.
• Feature documentation: Specifically looking for features designed to aid customer compliance, such as data retention controls, audit logs, and access management capabilities.

Hands-on testing:

Beyond what’s written, I explored the practical implementation of compliance features within the platforms. This involved:

• Audit log visibility: Assessing the detail and accessibility of logs that track user activities and system changes, which are vital for accountability and incident investigation.
• Account roles and permissions: Examining the granularity of user roles and how platforms (and users) control access to sensitive data and features. This is essential for adhering to the principle of least privilege.
• DPA access and signing process: Evaluating how easily a customer can access and execute a DPA with the provider.
• Data deletion options: Testing the mechanisms for customers to permanently delete their data (e.g., email logs, recipient lists) and understanding the retention policies in practice.

With all that, I could present a balanced view, distinguishing between stated policies and their functional implementation. In turn, you get the most relevant insights for your compliance strategy.

SMTP providers compliance detailed comparison

Here, I’ll break down each compliance category, comparing Mailtrap, Mailgun, SendGrid, Amazon SES, and Postmark based on my research and hands-on observations.

Regulations compliance: the global maze 🌎

Before the deep-dive, I’d like to give you the exact context since it’s easy to get lost in all the abbreviations and standards. 

When I talk about “regulations compliance”, I’m referring to SMTP providers’ inherent ability and demonstrable commitment to operate within the frameworks of major data protection and privacy laws worldwide. 

In my assessment, this means looking at their official stance, available documentation (like DPAs), and features that support your own compliance efforts regarding laws like GDPR, CCPA/CPRA, and, where applicable, HIPAA.

Here’s a direct comparison of how each provider approaches key regulations:

Interpretation: 

Here’s my take on what these comparisons mean for you:

• GDPR: I look for a clear DPA, transparency about data processing, and features that help me uphold data subject rights (like easy data deletion or access logs).
  • Mailtrap, Mailgun, SendGrid, and Postmark all offer dedicated DPAs and clear policies, making them solid choices. They provide the necessary contractual framework. Mailtrap’s focus on secure email delivery naturally integrates these principles. For more in-depth info on the subject check: A deeper dive into GDPR and Emails: How to Stay Compliant.     
  • Amazon SES inherits AWS’s compliance. While the underlying infrastructure is compliant, it places more responsibility on you to configure your services correctly for full GDPR adherence. This is suitable for those with strong DevOps teams who want ultimate control, but it might be a steeper learning curve for others.
• CCPA/CPRA: If you handle personal information of California residents, these acts are paramount. The focus here is on consumer rights: knowing what data is collected, opting out of its sale, and requesting deletion.
  • All five providers demonstrate alignment with these principles in their privacy policies and offer features that support your obligations. My review confirms that they understand the need for transparency and control. Again if you need more, check out how CCPA impacts your email strategy at CCPA Email Best Practices. 
• HIPAA: This one is highly specialized. If your business deals with Protected Health Information (PHI), a Business Associate Agreement (BAA) is a essential.
  • Mailgun, SendGrid, and Amazon SES explicitly offer BAAs and have well-documented capabilities for handling PHI environments. Amazon SES, being part of AWS, offers an extensive toolkit for building HIPAA-compliant architectures.
  • Mailtrap doesn’t directy support HIPAA, but we’re ready to review existing BAA of a client.
  • Postmark doesn’t support HIPAA.

Note: The topic has it’s fair share of intricacies. Therefore, it wouldn’t hurt to check our post on How to Ensure Your Email is HIPAA Compliant?

• CAN-SPAM Act: Its core tenets involve clear identification, opt-out mechanisms, and valid sender information. And keep in mind that, while often associated with marketing, CAN-SPAM also applies to transactional emails in certain contexts. 
  • All providers facilitate compliance here by supporting essential email authentication standards like SPF, DKIM, and DMARC, which are critical for sender reputation and deliverability. They also handle aspects like unsubscribe links. Ultimately, ensuring your email content and sending practices adhere to CAN-SPAM is largely your responsibility, but the providers give you the necessary tools. 

Further reading:

• A Quick Guide to Sending CAN-SPAM Compliant Cold Emails
• Legal Aspects of Email Marketing: Laws, Compliance, and Penalties

In essence, while all providers strive for general compliance, the depth of their support and the ease with which you can achieve compliance vary. For high-volume senders, the ability to easily sign a DPA, leverage granular controls, and have transparent data handling practices is a must-have.

Data residency and processing

Data residency refers to the physical or geographical location where an organization’s data is stored and processed. 

For high-volume email senders, particularly those operating across different continents or in highly regulated industries, the ability to choose data residency (or at least have transparency about it) could be critical. Why? Data residency may dictate the compliance with local laws and internal policies within a particular region. 

Data processing, on the other hand, describes how that data is handled, transformed, and managed throughout its lifecycle. And, just to stress, it’s as important as the residency. 

Here’s my comparison of how each SMTP provider addresses data residency and processing:

Interpretation:

• Data residency choice:
  • Mailtrap offers clear choices between EU and US data centers, which is a significant advantage for businesses needing to ensure their email data doesn’t leave a specific jurisdiction.
  • Mailgun also provides EU and US options, giving similar flexibility.
  • Amazon SES stands out with the vast number of AWS regions available globally. If you’re already operating within a specific AWS region, keeping your email data there simplifies your compliance landscape considerably. 
  • SendGrid operates globally, meaning the data might traverse or be processed in different regions for optimal deliverability. While they are compliant, explicit regional data residency choice for all data at rest could be less straightforward than with Mailtrap or Amazon SES.
  • Postmark primarily processes data in the US. This is perfectly fine for US-centric businesses.
• Data flow transparency:
  • All providers generally offer good transparency in their documentation regarding data flow. I pay close attention to DPAs and privacy policies to ensure no hidden routes or unexpected data transfers.
• Data Encryption:
  • I expected, and confirmed, that all these providers implement robust encryption at rest (when data is stored on servers) and in transit (when it’s moving across networks).
  • All five providers utilize industry-standard encryption protocols (AES-256 for data at rest, TLS 1.2+ for in transit). This ensures that even if data were intercepted or accessed without authorization, it would be unreadable.

Further reading: 

• Email Encryption: Everything You Need to Know
• StartTLS vs. SSL vs. TLS: Email Protocols Explained

In essence, if data residency is a hard requirement for your business (e.g., due to government contracts or specific industry regulations), providers offering explicit regional choices like Mailtrap, Mailgun, and Amazon SES should be at the top of your list.

For others, understanding the transparent data flow and robust encryption practices of all providers gives confidence in their security posture.

Auditing and accountability

Being able to prove WHAT happened WHEN is as vital as sending the email itself. Auditing and accountability refer to the mechanisms an SMTP provider puts in place to log activities, track changes, and ensure transparency in their operations and your usage of their platform. 

For me, this means:

• Readily available audit logs
• Clear incident response protocols
• Transparent sub-processor management 

These features are indispensable for internal governance, external audits, and forensic investigations in case of a security incident or compliance query.

Here’s my analysis of how each provider handles auditing and accountability:

Interpretation

For high-volume senders, robust auditing and a transparent accountability framework from your SMTP provider are non-negotiable. This enables you to maintain internal oversight, respond effectively to incidents, and confidently demonstrate your compliance posture to regulators and customers alike.

• Audit logs: These are your digital breadcrumbs. I rely on them to understand who did what, when, and from where. They’re crucial for security investigations, troubleshooting, and demonstrating due diligence to auditors.
  • All providers offer some form of audit logging. Amazon SES, benefiting from the entire AWS ecosystem, offers incredibly granular logging via services like CloudTrail, allowing for highly detailed activity tracking across your entire AWS infrastructure. 
  • Mailtrap, Mailgun, SendGrid, and Postmark also provide strong audit logging capabilities. They typically track user logins, API calls, setting changes, and other critical account activities. 
• Log retention: How long are those logs kept? This is vital for meeting regulatory requirements (e.g., GDPR mandates records of processing activities).
  • Most providers offer configurable log retention periods, from a few days up to several months or even years, depending on the service tier and specific log type. For instance, Mailtrap allows for configurable retention, which is essential for aligning with various compliance policies. Amazon SES gives you the most flexibility, allowing you to store logs in S3 for virtually as long as you need. This flexibility is key for organizations with long-term audit requirements.
• Incident response transparency: How quickly and clearly does the provider communicate in the event of an outage or security breach?
  • I look for publicly available status pages and documented incident response plans. All providers maintain status pages and have internal protocols. SendGrid and AWS (for SES) often publish more detailed transparency reports or security bulletins, reflecting their scale and commitment to a wide user base. 
  • Sub-processor Transparency: All five providers maintain publicly accessible lists of their sub-processors. This transparency demonstrates their commitment to accountability and allows you to perform your own due diligence on their supply chain.
• Compliance Reports/Certifications: These third-party attestations (like SOC 2, ISO 27001) are independent validations of a provider’s security and compliance posture.
  • Amazon SES, as part of AWS, benefits from the broadest range of certifications, covering virtually every major compliance framework. 
  • Mailgun, SendGrid, and Postmark all hold SOC 2 Type 2 reports, which is a strong indicator of their robust internal controls over security, availability, processing integrity, confidentiality, and privacy.
  • Mailtrap has ISO 27001 and is pursuing SOC 2, showcasing its commitment to these rigorous standards as its platform scales. These certifications aren’t just badges; they represent a deep commitment to maintaining high security and operational standards. 

If you’d like to learn more about this security aspect check our blog posts: Understanding Secure Email Server: A Comprehensive Guide and SMTP Security Best Practices: A Comprehensive Guide.

In summary, for large-scale email senders, robust auditing and a transparent accountability framework from your SMTP provider are the key. This enables you to maintain internal oversight, respond effectively to incidents, and confidently demonstrate your compliance posture to regulators and customers alike.

Wrapping it up

I hope you found this SMTP providers compliance comparison insightful and interesting. Please note that this article presents only a part of an original and complete analysis published on Mailtrap Blog. Visit us there to explore this topic in more detail!