Nitrosend vs Mailgun.

TL;DR

Mailgun is a transactional email API with a long deliverability track record, EU data residency, and inbound routing. If the job in front of you is moving receipts and password resets at volume, it does that job well and has done for over a decade, at a price that's hard to argue with.

Nitrosend is an AI-native email platform wearing a similar badge. It sends transactional mail too, and it also runs campaigns, flows, and segments, every one of them an MCP tool before it's a screen. If you're running marketing alongside the transactional stream and you already work through an agent, Mailgun covers the transactional half only, so the campaigns go to a second product and the reporting never sits in one place.

The same split is what teams end up weighing against Mailjet, Mailrelay, and Mailshake, each of which owns a different slice of the program.

1. Add and verify your sending domain in Nitrosend. DKIM and SPF records sit alongside Mailgun's, so both can send from the same domain during the overlap.
2. Start with one low-stakes message type, a receipt or a password reset, sent with nitro_send_message. Watch it for a week before anything else moves.
3. Import contacts with nitro_import_contacts. Email, first and last name, and custom properties map straight across from a Mailgun list export, and there's no contact cap on the other side to import under.
4. Rebuild anything scheduled as a flow with nitro_compose_flow. Mailgun has no flow builder to port, so this is usually the first time the sequence has existed as one object rather than as a cron job and a send call.
5. Keep the reputation you already built. BYO sending keys on Pro and above route sends through Mailgun, SES, Resend, Postmark, or SendGrid while Nitrosend runs the platform, so the warmed IP and the sending history stay exactly where they are.

• Unlimited contacts on every plan, including Free, so there's no contact-count tax as the list grows.
• Marketing and transactional email in one platform, with the two streams kept deliverability-isolated.
• Campaigns, flows, and segments sit beside the transactional stream, so a team running both stops paying two vendors and reconciling two sets of analytics.
• MCP-first is an architecture rather than an integration: every capability is an API endpoint and an MCP tool before it's a screen.
• The MCP covers campaigns, flows, contacts, templates, and segments, which is the whole platform rather than the sending half of it.
• Deliverability, billing, tests, and approvals are tools too, and they're the four that usually stop an automation dead.
• The complaint rate, the bounce split, and the domain reputation are readable by the same agent that sends the mail.
• An agent can draft a campaign, segment the audience, run the test, and hold the send for approval without a person opening a screen.
• Transactional sends deliberately stay on the REST API, because a send that has to be fast shouldn't wait on a tool call.
• A clean REST API and a CLI sit alongside the MCP, so nobody is forced through an agent to get work done.
• BYO sending keys on Pro and above route your mail through Amazon SES, Resend, Postmark, Mailgun, or SendGrid, on the domain and IP you already warmed.
• That makes the decision reversible, where switching platforms otherwise means switching sending reputation on the same day.

What this comparison actually turns on.

Both products put mail in inboxes, so reliability isn't the deciding line here. The line is how many products your email stack needs and who gets to drive them. Mailgun is built around the transactional half: a message goes out, a webhook comes back, and the logs say what happened to it. The campaign, the segment, and the flow that fires three days later live in something else, and they report in something else.

Why that gets expensive once an agent is driving.

The split costs almost nothing while a person is the one moving between the two screens. It starts costing something the moment an agent is doing the work, because the agent has to carry two sets of credentials, two contact models, and two definitions of an unsubscribe, then reconcile the numbers itself before it can tell you anything useful. None of that is Mailgun's fault. It's what a product scoped to transactional sending is for, and it's the reason we built the other shape instead of a marketing add-on.

If that's where you are, a transactional API doing its job well and a second product carrying the campaigns, Nitrosend is the version where both halves answer to the same agent. Receipts keep going out through nitro_send_message, the campaign that used to live somewhere else gets built with nitro_compose_flow, and the free tier is enough to run the two side by side for a week before you commit to anything.

Does Nitrosend have an MCP server, and how is it different from Mailgun's?

Both exist, and the difference is scope rather than quality. Mailgun's official open source server wraps its sending API, so an agent can reach everything to do with getting a message out and finding out what happened to it. Nitrosend's wraps the whole platform, so an agent can also reach the marketing side and the operational controls around it, which is the part that usually forces a person back to a dashboard. The transactional send is the one thing we deliberately left on REST, so nothing time-critical waits on an agent's turn.

Can Nitrosend replace Mailgun for transactional email?

For outbound, yes. Single-recipient sends, async status polling, and idempotency keys are all there. What it can't replace is inbound: Nitrosend is sender-side, so anything routing replies or feeding an inbound webhook stays on Mailgun.

Can I keep sending through Mailgun and still use Nitrosend?

Yes, and it's the migration path we recommend. BYO sending keys on Pro and above route sends through your existing Mailgun account, so the reputation and the deliverability history stay put while the campaigns, flows, and segments move.

Does Nitrosend offer EU data residency?

Not as a documented option. If EU residency is a requirement rather than a preference, Mailgun is the answer here and this page isn't going to argue otherwise.