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Hyvor Relay vs KumoMTA (2026): which should you pick?

As of Nov 13, 2026, KumoMTA grades higher than Hyvor Relay: 2.2 against 1.8 out of 4.0.

Checked Nov 13, 2026 · graded Nov 13, 2026 by ToolGPA

KumoMTA grades higher on the free plan and features. They get the same grade on value for money, ease of use and platforms.

Price, platforms and features side by side. The table says where each price was read and when.

Hyvor Relay

Open-source email API you can self-host

Free plan · from €10,000/yr
Full detailsrelay.hyvor.com

KumoMTA

Open-source mail server for high-volume, self-run email sending

Free plan · from $5,000/yr
Full detailskumomta.com

Which one is for you

Pick Hyvor Relay if

  • Fits if you can run your own mail servers and want no per-email fee
  • Works for teams that need the open-source license for compliance

Look elsewhere if

  • Skip it if you do not run servers, as self-hosting leaves deliverability to you
  • Watch out: the hosted cloud plan is a waitlist and its €30 a month is an estimate, not final
  • Pricey if you need to avoid the AGPL-3.0, since the Enterprise License starts at €10,000 a year
  • Tight if you need long logs, with delivery logs kept for 30 days

Pick KumoMTA if

  • Fits if you're an engineering team running your own high-volume sending
  • Works for senders moving off a commercial mail server who can write Lua

Look elsewhere if

  • Skip it if you want a point-and-click setup, since configuration is done in Lua
  • Tight if you need support: Silver is business hours only, and Enterprise has no published price
  • Not for you if you want a hosted service, as you run it yourself
  • Watch out: the pages don't say which operating systems are supported

How we grade them

1.8GPAHyvor RelayWeak2.2GPAKumoMTAFair
Value for money
CFree only if you host it yourself, which needs servers and IPs, so it sits in the middle. The Enterprise License starts at €10,000 a year, and the cloud plan is an unconfirmed estimate.
CThe software is free under Apache 2, but you host it yourself, and paid support starts at $5,000 per billion messages a year.
Free plan and trial
CThe open-source edition is free with unlimited usage, but you must run it yourself, and there is no hosted free tier.
BEvery feature is free to run, with community help on Discord. You do need your own server to use any of it.
Features
CEmail API, DKIM domains, webhooks, bounce and complaint handling, projects and observability. Delivery logs last 30 days.
BHigh-volume sending, Lua policy scripting, traffic shaping and IP pools, with hooks into Kafka, AMQP, Prometheus, Grafana and Vault. Nothing in the listing shows a gap in the job.
Ease of use
DNo rating on record. Self-hosting means servers, DNS, IP reputation and deliverability are yours to run.
DNo store rating on record. It's configured in Lua scripting on your own servers, so it suits engineers.
Platforms and integrations
CWeb interface and API, with Prometheus, Grafana and Docker Swarm hooks. No apps.
CSoftware for your own servers, listed for Linux, with Docker and Kubernetes. No dashboard or hosted version.
Best forself-hosted open-source email sendinga free high-volume mail server you run yourself

The GPA is the average of the five grades: an A is 4 points, an F is none. The full reasons are on each tool's page: Hyvor Relay and KumoMTA. How we grade

Price against what you get

Hyvor Relay starts at about $931 a month and scores 1.7 out of 4 on features, ease of use and platforms. KumoMTA starts at $416.67 a month when paid by the year and scores 2.0.

KumoMTA scores higher and starts $514.33 a month lower. Of the other email sending services on the chart, 41 score higher than Hyvor Relay for less, and 30 score higher than KumoMTA for less.

Features, ease of use and platforms, averaged

D1.0C2.0B3.0A4.0Free$1$2$5$10$20$50$100$200$500$1kMore for lessCosts more, scores moreCosts less, scores lessCosts more, scores lessHyvor RelayKumoMTA

What paid plans start at, a month (each step along is roughly double) →

  • The best score at each price
  • Has a free plan
  • No free plan
The full chart of email sending services, and the best at every price

Where they differ

    In commonFree planOpen sourceSelf-hostablePublic APITransactional email

    At a glance

    Hyvor RelayKumoMTA
    PricingFree planFree plan
    Starts at€10,000 per year and up (Enterprise License)$5,000 per billion messages per year for Silver support
    Free planSelf-hosted open-source edition: free with unlimited usage under AGPL-3.0 and community support.The software and all its features are free under the Apache 2 license; community support runs through a Discord server.
    Free trialNone listedNone listed
    Web
    Linux
    Made byHyvorKumo Corp
    Price read fromrelay.hyvor.comkumomta.com
    CheckedNov 13, 2026Nov 13, 2026

    Worth knowing

    Hyvor Relay

    • The cloud plan is on a waitlist, listed at an estimated €30 per month for 300,000 emails and not yet final.
    • Self-hosting means running servers, IPs and deliverability yourself.
    • Delivery logs are kept for 30 days.
    • The page states the Enterprise License starts at €10,000 a year and is priced by volume.

    KumoMTA

    • It is software you run yourself on your own servers; the pages do not say which operating systems are supported.
    • Support is priced per billion messages a year with no server limit; Silver is business hours only, and Enterprise has no published price.
    • Configuration is done in Lua scripting, so it suits engineers, not a point-and-click setup.

    Key features

    Hyvor Relay

    Email API
    A REST API with idempotent sends, HTML and plain text, attachments, custom headers and multiple recipients.
    Domains and DKIM
    Multiple sending domains with enforced DKIM signing and an in-built DNS server.
    Webhooks
    Event webhooks for deliveries, bounces and domain verification.
    Bounce and complaint handling
    Bounces, complaints and suppressions are managed automatically.
    Projects
    Isolated projects each with their own domains, keys and webhooks.
    Observability
    Prometheus and Grafana integrations and health checks for servers, DNS and IP reputation.

    KumoMTA

    High-volume sending
    The vendor says a single server can send several million messages an hour, and that it can scale out with Docker and Kubernetes.
    Lua policy scripting
    Behavior is set in Lua scripts, with policy helpers for common configurations.
    Integrations for operations
    Supports webhooks, AMQP, Kafka, Vault, Prometheus, Grafana and direct database access.
    Traffic shaping and IP pools
    A customer quote on the site names traffic shaping and IP pool automation as the parts it builds on.
    Migration guides
    The site has a migration center with pages for moving from Momentum, PowerMTA, Halon, SendGrid and Hurricane MTA.
    Open source
    Released under the Apache 2 license, with the source code on GitHub.

    Plans

    Hyvor Relay

    • Self-Hosted Open-Source$0

      You host it yourself under AGPL-3.0, with all features and community support.

    • Enterprise License€10,000

      per year and up

      The same features without AGPL-3.0 obligations, with volume-based pricing, enterprise support and SLA options.

    KumoMTA

    • Community$0

      Free software with every feature. Help comes from the community Discord server; you host it yourself.

    • Silver$5,000

      per billion messages per year

      Business-hours support (9-5 US Eastern) by email and portal, a shared sponsor Discord channel and help with basic configuration.

    • Gold$10,000

      per billion messages per year

      Support 8-7 US Eastern, a 24/7 critical-issue SLA, a private Discord and help with custom Lua policy.

    • EnterpriseCustom

      24/7/365 support, telephone support, a private Discord or Slack channel and refactored policy scripts. No price is stated; contact the vendor.

    Common questions

    Which is cheaper, Hyvor Relay or KumoMTA?

    As of Nov 13, 2026, KumoMTA is cheaper to start with: $416.67 a month when paid by the year, against about $931 a month for Hyvor Relay. Hyvor Relay starts at €10,000 per year and up (Enterprise License), and KumoMTA starts at $5,000 per billion messages per year for Silver support.

    Which has a free plan, Hyvor Relay or KumoMTA?

    As of Nov 13, 2026, both Hyvor Relay and KumoMTA have a free plan.

    Which platforms do Hyvor Relay and KumoMTA run on?

    As of Nov 13, 2026, only Hyvor Relay lists a web app and only KumoMTA lists a Linux app. A platform missing from a listing is one its maker's pages did not mention.

    More comparisons

    How this page was made

    • The verdict at the top follows a fixed rule. When both tools are in the same category and either is in our top three for it, the verdict follows that ranking: the higher-placed tool is our pick. The top three weigh who each tool suits as well as its grades, so a pick can go against the GPA. Otherwise the page does not pick one and says which grades higher: the higher GPA first; on a tie, the one with a free plan, then the one that starts cheaper in dollars a month, counted the same way for both; if they are still level, what the choice depends on.
    • The grades are our own, from each tool’s review or report card. The GPA is their average.
    • Prices, plans and platforms come from each tool’s listing. The table above says where each price was read and when.
    • The differences and the answers to the questions are worked out from those listings.
    How we review and grade