SMTP: A Reliable, High-Volume SMTP Email Relay and API for Senders

You can write the perfect email, segment your list with care, and time the send to the minute. None of it matters if the message lands in spam or never arrives at all. For teams sending password resets, purchase confirmations, and platform notifications, a delayed or undelivered email is not a marketing miss. It is a broken product experience. And once your domain or sending IP picks up a poor reputation with mailbox providers, digging out is slow and expensive.

The problem compounds at scale. A few thousand sends a month is forgiving. Millions of sends per month expose every weakness in your infrastructure: latency on triggered messages, bounces that erode your reputation, and shared mail queues that throttle your throughput when you need it most.

SMTP

SMTP is a suite of email delivery, SMTP relay, and API solutions built for reliability, scale, and security. It handles billions of emails a month with 99.99% uptime, giving high-volume senders a delivery backbone they can build a business on.

The platform earns its place by solving the part of email most tools ignore: getting the message into the inbox. Whether the priority is near-zero latency for transactional sends or sustained throughput for millions of marketing emails, SMTP scales to meet the load without forcing you onto a shared queue.

Migration to SMTP is handled by an in-house team that moves customers off providers like 1 a setup wizard. When something needs a human, support is staffed by people who make a living from email delivery.

Here is what you get under the hood.

• Custom API Integrations: Hands-on development help from SMTP’s team to map your existing setup and build the integration alongside you.
• Dedicated IP: Available from the Starter plan up, a dedicated Internet Protocol (IP) address keeps your sending reputation isolated from other senders.
• Email List Validation: A big data-driven service that cleans your audience list to cut bounces before they happen.
• Email Relay API: A RESTful application programming interface (API) designed for fast integration, with documentation built to get you sending in roughly five minutes.
• Insight Engine: An optional add-on that enriches customer profiles with data, opening up more ways to engage and monetize your list over email. Available on all plans at 20% of the plan cost.
• Managed Delivery: Fully managed high-volume sending for teams that want inbox placement handled for them.
• Managed Migration: API mapping and migration templates that move you off another provider without disrupting live sending.
• Reputation Defender: SMTP’s proprietary technology that monitors list health in real time and suppresses bad addresses before they trigger soft or hard bounces, protecting your domain and IP standing with ISPs. Available on all plans at 20% of the plan cost.
• Reporting: Detailed delivery reporting is included on every plan.

Taken together, these pieces cover the full arc of a send, from validating the list before launch, to isolating your reputation on a dedicated IP, to suppressing risky addresses in real time and reporting on what landed. That is the difference between hoping your email arrives and knowing it does.

Our customers typically see about a 60% increase in delivery rates and 3x the ROI after moving from other providers.

Getting Started with SMTP

SMTP scales from a starter plan up to dedicated high-volume infrastructure, so you can begin small and grow into it. Plans start at 50,000 emails per month for just $25 US, with Reputation Defender available as an add-on across all tiers. If your volume runs into the hundreds of millions, the high-volume tier offers a dedicated platform instance, your own mail transfer agent, and no shared queue. Pick the plan that matches where you are now, and let the infrastructure carry you to where you are going.

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Frequently Asked Questions