Nitrosend vs Courier.

TL;DR

Courier is notification infrastructure. One API call takes a product signal and routes it to whichever channel each recipient prefers, across email, SMS, push, an in-app inbox, and chat in Slack, Microsoft Teams, or WhatsApp, over provider accounts you connect yourself. If your notifications genuinely run across five channels, that's the job Courier does, and Nitrosend doesn't do it at all.

Nitrosend sends. The mail is ours to deliver, on a domain we authenticate, with campaigns, flows, and segments sitting beside the transactional stream, and every one of them is an MCP tool before it's a screen. Contacts are unlimited on every plan. If you bought notification infrastructure and then found that your notifications were email, you're paying an orchestration fee on top of a transport.

Once the marketing half enters the sum, the shortlist widens, and the Dotdigital comparison, the Drip comparison, and the Emailchaser comparison cover the platforms that price that half on contacts held rather than notifications routed.

1. Leave the non-email channels where they are. SMS, push, the in-app inbox, and chat in Slack, Teams, or WhatsApp stay on Courier. Nothing in this migration touches them, and there's no end state in which they come across.
2. Add and verify your sending domain in Nitrosend. The DKIM and SPF records sit alongside the ones your current provider already uses, so both routes can send from the same domain for as long as the overlap runs.
3. Move one email type first. A receipt or a password reset, sent with nitro_send_message, and watch it for a week before anything else follows it.
4. Bring the people across and rebuild the sequences. nitro_import_contacts takes Courier's lists and audiences as a contact export, and nitro_compose_flow rebuilds the journey. There's no campaign or segment object to port, so this is usually the first time the audience exists as one thing rather than as a set of routing rules.
5. Point BYO at the provider you were already sending through. BYO sending keys on Pro and above route mail through Amazon SES, Resend, Postmark, Mailgun, or SendGrid. Courier isn't a transport itself, so if the account behind it is one of those five, pointing at it keeps the sending reputation exactly where it is.

• Sending is included, so there's no separate provider account to hold and no second bill for the same message.
• Unlimited contacts on every plan, including Free, so a list that grows without being mailed never moves the bill.
• Campaigns are a first-class object rather than a one-off broadcast on a single channel.
• Flows with triggers, steps, and branches can be composed by an agent, not just fired by one.
• Segments are agent-reachable, so an audience can be defined and mailed in the same pass.
• Contacts carry custom fields, a timeline, and enrichment on the record itself.
• MCP-first is the architecture and not an integration: every capability is an API endpoint and an MCP tool before it's a screen.
• A REST email API and a CLI sit beside the MCP, so nobody is forced through an agent to get work done.
• Marketing and transactional email run on one plan and one ladder.
• BYO sending keys on Pro and above route mail through Amazon SES, Resend, Postmark, Mailgun, or SendGrid, on a domain and IP you already warmed.
• Between the three founders, our team has sent more than 6 billion emails across two companies that were both acquired.

Two MCP servers, and only one of them sends

Courier ships a hosted MCP server at mcp.courier.com. You add it to a client with an API key in a header, and the tools cover sends, delivery tracking, users, audiences, journeys, and preferences. It sits on the free Developer tier, so an agent can drive a Courier account before anybody has upgraded anything.

So the difference isn't breadth. It's what sits underneath. When an agent composes a journey in Courier, the message is handed to the SendGrid, Mailgun, or SES account you connected, and that account is the one that actually carries the send. The Nitrosend MCP server exposes campaigns, flows, contacts, and segments on a platform that does the sending itself, so drafting the mail and sending it sit behind one account instead of two. Retrofitting an agent onto a dashboard leaves it driving a surface that doesn't do the work, and an agent that can only reach the layer above the send is the same defect wearing an API.

For a product whose notifications really are five channels wide, those two are complementary more often than they're alternatives. For a team whose notifications are email, one of them is a layer being operated twice.

What a routed message actually costs

Courier prices on notifications sent: $0.005 each on Business, with a free tier at 10,000 a month. That number buys the orchestration, not the delivery. The provider account behind it charges its own rate for the same message, so the real unit cost is two line items on two bills, and a forecast built from one of them comes in short.

That's a fair trade when the routing is doing real work, across several channels and a preference model that would otherwise be application code. It's harder to defend when nearly all the volume is email and the routing decision is the same one every time. At that point you're paying a per-send fee to hand your mail to a transport you already pay, and the campaigns, flows, and segments you actually wanted next are what Nitrosend puts on one bill behind one send.

Can Nitrosend replace Courier?

Not for SMS, push, the in-app inbox, or chat, because Nitrosend specializes in email. For the email half, yes: transactional sends, campaigns, flows, and segments on a platform that does its own delivery. For most accounts that half is most of the volume, and the Courier account stays open for the rest.

Courier has an MCP server too. What's different about Nitrosend's?

Both are hosted and both authenticate with an API key, so the difference isn't the connection or the tool count. It's the account underneath: Courier's MCP drives orchestration over a provider you hold separately, and Nitrosend's drives the platform that sends. One account instead of two vendors.

Do I still need a SendGrid or SES account with Nitrosend?

No. Sending is included in the plan, so there's no provider account to hold and no second bill for the same message. BYO sending keys on Pro and above can route through Amazon SES, Resend, Postmark, Mailgun, or SendGrid if you want to keep a reputation you've already warmed, but that's an option rather than a requirement.

Does Nitrosend have an in-app inbox or a preference center?

No to both. Nitrosend specializes in email, so neither an embeddable in-app feed nor a per-topic, per-channel preference center is part of it. If preferences across five channels are the requirement, Courier does that job.