Everything you need to know about email infrastructure in 2025

You’ve probably heard people saying that email is only a supplementary tool nowadays, but is that really true? Not at all.

Email infrastructure is the foundation of modern communication, acting as the unseen engine that powers billions of emails sent daily. In 2025, as email continues to dominate professional correspondence, the intricacies of email infrastructure have become more nuanced and essential than ever.

This guide explores its core components, the delivery process, critical authentication protocols, advanced monitoring techniques, and how to set up a resilient system that meets today’s demands. Let’s jump right in, shall we? 

What is email infrastructure?

Email infrastructure encompasses the systems, tools, and processes required to send, deliver, and receive emails reliably and securely.

It includes hardware such as mail servers, software that handles communication protocols, email clients and authentication mechanisms to ensure trust, and monitoring systems to maintain optimal performance.

For instance:

When you’re using email, you’re not just using the app. For it to work, you need the email provider's servers, email protocols and internal authentication systems. Encryption is also included.

In 2025, the sophistication of email infrastructure has grown beyond mere facilitating communication. It must now address evolving challenges such as cyberattacks, stricter privacy regulations, and the sheer scale of global email traffic.

Hence, understanding email infrastructure isn’t just for IT professionals. Marketers, business owners, and even individuals who rely on email for outreach or communication benefit from grasping its essentials. A robust infrastructure isn’t just about sending emails—it’s about ensuring they reach the recipient’s inbox without delay, distortion, or security risks.

The email delivery process

The path an email takes from sender to recipient is more complex than it appears. On the surface, it seems like just sending a plain SMS message back in the day. While it happens in seconds, multiple steps and systems are involved. Overall, there are five separate steps your message has to go through before being sent:

1. Mail transfer agent (MTA): When you hit "send," your email is handed off to an MTA, a server that acts as the delivery driver for your message. The MTA determines the recipient’s mail server and prepares the email for transit.

2. DNS lookup: The MTA uses Domain Name System (DNS) records to locate the recipient’s mail server. This process includes querying the recipient’s domain for Mail Exchanger (MX) records, which specify the destination server.

3. SMTP communication: The Simple Mail Transfer Protocol (SMTP) governs how the sending and receiving servers communicate. During this handshake, the sender’s server confirms the recipient’s address and transfers the message, often encrypted with STARTTLS for security.

4. Spam and filter checks: Once the email reaches the recipient’s server, it undergoes scrutiny. Spam filters analyze content, sender reputation, and authentication to decide whether the email is safe and relevant. These checks determine whether the message lands in the inbox, promotions tab, or spam folder.

5. Final delivery: After clearing these hurdles, the email reaches its destination. However, delivery success depends on multiple factors, from proper configuration to the sender’s domain reputation.

Evolving email authentication protocols

Email authentication is the backbone of trust in digital communication. It’s essentially the system running an ID check for the sender and their device. Without it, emails are susceptible to spoofing, phishing, and other malicious activities. In 2025, several protocols work in tandem to ensure the authenticity of emails, with the most important being:

SPF

SPF (Sender Policy Framework) prevents unauthorized entities from sending emails on behalf of your domain. It validates the sender’s IP address against a list of authorized servers published in the domain’s DNS records. If the IP isn’t on the list, the message doesn’t end up being sent.

DKIM

DKIM (DomainKeys Identified Mail) ensures that the content of an email remains unchanged during transit. It attaches a cryptographic signature to the email header, allowing the recipient’s server to verify its integrity.

DMARC

DMARC (Domain-based Message Authentication, Reporting, and Conformance) builds on SPF and DKIM, aligning their results to enforce a policy on how unauthenticated emails are handled. It also provides detailed reports, offering insights into potential vulnerabilities.

BIMI

As email clients increasingly support BIMI (Brand Indicators for Message Identification), businesses can display their verified logos in recipients’ inboxes, enhancing brand visibility and trust. While not as essential as SPF or DKIM, BIMI is still crucial in email authentication.

Types of Email Infrastructure

Email infrastructure is not a one-size-fits-all solution. Organizations usually choose between two primary setups based on their needs, resources, and goals:

On-premise infrastructure

On-premise setups involve hosting email servers within an organization’s data center. This option offers complete control over data, configurations, and security protocols. However, it requires significant investment in hardware, maintenance, and IT expertise. Businesses with strict compliance requirements, such as those in finance or healthcare, often opt for on-premise solutions.

Cloud-based infrastructure

Cloud-based systems leverage third-party providers like Zoho Mail to handle email delivery. These services offer scalability, cost-effectiveness, and built-in redundancy, making them ideal for high-volume senders. The trade-off is reduced control, as data resides on external servers. Providers mitigate this by implementing robust security measures and offering advanced configuration options.

How to optimize email deliverability

Deliverability is the ultimate test of email infrastructure. Even a perfectly crafted email is useless if it doesn’t reach the recipient. To optimize deliverability, consider:

Technical foundation

A properly configured infrastructure is critical. Authentication protocols, a dedicated IP address, and a clean sending domain are non-negotiable. Whether you’re using an on-premises server or working with a third-party provider, these essentials come first.

You don’t want to run into deliverability issues during crucial campaigns or be unable to communicate with key partners. 

Content strategy

Email content must align with best practices. These change all the time, so you’d best listen to experts, as well as any official communication from service providers.

For the most part, these best practices mean you have to avoid spam triggers, maintain a professional tone, and prioritize value for the recipient. Additionally, it’s advised to send emails that are mobile-friendly, as a significant portion of users read emails on their phones.

Reputation management

Regularly monitor your domain’s reputation using tools like Google Postmaster Tools or Microsoft SNDS. High bounce rates, spam complaints, and irregular sending patterns can damage your reputation and limit your deliverability.

As of 2025, it’s not 100% clear what constitutes email reputation, but experts generally agree you ought to avoid links, generic phrases or sending excessive messages to one address. Basically, don’t spam, provide value and be moderate, and your reputation should stay intact.

Email monitoring in 2025: Techniques you should use

Real-time monitoring is the linchpin of a resilient email infrastructure. If you notice issues once they’ve already occurred, it’s usually too late and the domain might very well be unsalvagable.  Monitoring tools provide insights into performance, security, and deliverability. Focus on:

Bounce management

Analyze bounced emails to identify invalid addresses, full mailboxes, or server issues. Differentiate between hard bounces (permanent) and soft bounces (temporary). The best way to do this is to use third-party tools, especially if it’s an important transactional email.

Feedback loops

Many email providers offer feedback loops, allowing senders to track spam complaints. Promptly addressing complaints helps maintain reputation. Obviously, the ideal solution would be to not even risk it, as some complaints are harder to address than others.

Anomaly detection

Sudden changes in open rates, click-through rates, or bounce rates can indicate issues with infrastructure, content, or reputation. Pick a sufficiently long time period and use it as a reference for tracking these metrics.

Email marketing tools like Zoho Campaigns offers detailed analytics dashboards that track key performance metrics such as open rates, click-through rates, and bounce rates. These dashboards provide a clear view of how your emails are performing, allowing you to identify patterns or issues quickly.

For example, Zoho Campaigns enables users to monitor recipient engagement over time and detect anomalies, such as sudden spikes in spam complaints or drops in deliverability. Its real-time reporting features also help pinpoint problems related to specific campaigns, offering actionable insights to refine strategies and improve email performance.

How to set up a robust email infrastructure

While there’s a plethora of nooks and crannies you have to dig into, the setup process itself is relatively straightforward and can be distilled into five steps:

1. Domain setup: Start by securing a dedicated domain for email communication. Configure DNS records for SPF, DKIM, and DMARC to establish a secure foundation.

2. Choose your tools: Whether you opt for on-premise servers or a cloud-based provider, ensure the solution aligns with your needs. Factor in scalability, security, and budget.

3. Authenticate and encrypt: Implement authentication protocols and enforce TLS encryption to protect emails in transit. Of course, if you’re dealing in sensitive or confidential subject matter, additional encryption might be required.

4. Monitor and optimize: Continuously track performance metrics and adjust configurations to address emerging issues. Use feedback loops and analytics tools to stay informed.

5. Stay updated: Email infrastructure isn’t static. Regularly update software, refresh IP addresses, and adapt to new protocols or regulations. Most importantly, keep track of known spam triggers and make sure to remove them from your campaigns. 

Conclusion

In 2025, email infrastructure is not just a technical requirement but a strategic enabler of communication and business success. Innovations like AI-driven deliverability optimization, zero-trust email frameworks, and edge computing are shaping its future.

Therefore, you have no excuse to view email as just picking a domain and a service provider. If you get to know how each node in this system works, you’ll be able to make your campaign more efficient than ever before.