mxsin.com
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Email platform

Send, receive and host email
on your own domain.

mxsin.com brings transactional and marketing sending, inbound mail and hosted mailboxes together in one place, with authentication and deliverability tools built in from the start.

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Why teams choose mxsin

One platform

Sending, receiving, mailboxes and webmail share one account, one dashboard and one set of domains.

Deliverability first

DKIM signing, guided DNS, warm-up, automatic limits and reputation monitoring protect every message you send.

Built for developers

A clean JSON API, SMTP relay, signed webhooks and official client libraries get you live quickly.

Clear and in control

Live DNS ticks, message search, sending health and audit logs show exactly what is happening.

Everything included

Every feature below is available in the platform today.

Sending

  • REST API and SMTP relaySend from any stack over a simple JSON API or standard SMTP with your own credentials.
  • Bulk sendSend to many recipients in one API call, each with their own personalised fields.
  • TemplatesStore reusable templates with variables and send them by name.
  • Message streamsKeep transactional and broadcast mail apart, each with its own settings and tracking.
  • Open and click trackingOptional, per domain, on your own tracking host.
  • Test sendSend a test message from the dashboard before going live.

Domains and authentication

  • Domain verificationAdd a domain, publish the records shown, and check them with one click.
  • DKIM signingEvery message is signed with your own domain key.
  • SPF and DMARC guidanceThe exact records to publish, with live ticks when they are in place.
  • Custom return addressUse your own MAIL FROM subdomain so bounces align with your domain.
  • DNS setup wizard and drift alertsA step-by-step wizard, plus a warning if a record later changes or disappears.

Audience and compliance

  • Contact lists and topicsOrganise contacts into lists and let them choose the topics they want.
  • One-click unsubscribeStandard List-Unsubscribe headers and a hosted preference page.
  • SuppressionsBounces, complaints and unsubscribes are suppressed automatically, with your own list on top.

Events and integrations

  • WebhooksSigned, retried event delivery for sends, deliveries, bounces, complaints, opens and clicks.
  • Slack-compatible destinationsPost events straight into a chat channel.
  • Scheduled exportsCSV exports of events and messages, kept for download or pushed to your endpoint.
  • Message search and activityFind any message and see every event that happened to it.
  • API request logSee each API call your account made and its response.

Receiving mail

  • Inbound to webhookReceive mail for your domain as JSON posted to your app.
  • Routing rulesPer-address routes to a webhook, a forward or a mailbox, with a catch-all for everything else.
  • Forwards and aliasesPoint any address at another inbox in seconds.

Hosted mailboxes

  • Mailboxes on your domainReal IMAP and SMTP mailboxes with storage you control per account.
  • WebmailA clean browser mail client with your mailboxes one click away.
  • Mailbox managerAccount owners add mailboxes, aliases and passwords themselves.
  • Calendar and contactsCalDAV and CardDAV sync with the same sign-in.
  • Mail-app auto-setupAutoconfig, autodiscover and SRV records, plus Apple configuration profiles for iPhone, iPad and Mac.
  • Mail importBring old mail across from another IMAP account.
  • App passwordsSeparate passwords for phones and mail apps when two-step verification is on.
  • ThemesChoose Midnight, Burnt orange or Glass for the mailbox pages.

Deliverability

  • Sending healthBounce and complaint rates against safe thresholds, with in-panel alerts.
  • Provider breakdownDelivery results split by the major mailbox providers.
  • Automatic sending limitsLimits that grow with good sending and protect your reputation when something goes wrong.
  • Warm-upNew sending capacity is brought up gradually and paused automatically if signals turn bad.
  • DMARC and TLS reportsAggregate reports collected and summarised for you.
  • Reputation and blocklist monitoringRegular checks against public blocklists, with alerts.

Accounts and security

  • Team accessInvite colleagues with their own sign-in and a role inside your account.
  • Two-step verificationAuthenticator-app codes with recovery codes.
  • PasskeysSign in with a passkey or security key.
  • Session controlSee every signed-in device and sign any of them out.
  • API keys and SMTP credentialsCreate, name and revoke as many as your plan allows.
  • Audit logA record of important account and admin actions.
  • Invoicing and billingInvoices with PDF download inside the dashboard.

Coming soon

  • Android appManage your mailboxes and sending from your phone.

How it works

  1. Request accessTell us about your sending and we set up your account.
  2. Add your domainPublish the DKIM, SPF and DMARC records shown, and watch the ticks turn green.
  3. Connect your appCreate an API key or SMTP credentials and send your first message.
  4. Grow with confidenceWarm-up, automatic limits and health monitoring keep your reputation strong as volume rises.

For developers

Send with a single request, receive mail as JSON and react to every event.

  • REST API for sending, bulk sending, templates, lists, suppressions and events
  • SMTP relay with your own credentials
  • Signed, retried webhooks
  • Official client libraries for PHP, Node.js and Python
  • Full API reference and an API request log
Read the docs
POST /v1/send
Authorization: Bearer mx_…

{
  "from": "hello@yourshop.com",
  "to": "customer@example.com",
  "subject": "Your order has shipped",
  "html": "<p>Thanks for your order!</p>"
}

Security and compliance

Strong sign-in

Two-step verification, passkeys, recovery codes, device lists and remote sign-out.

Authenticated mail

DKIM on every message, SPF and DMARC guidance, encrypted connections and DMARC and TLS reporting.

Permission-based sending

Automatic suppressions, one-click unsubscribe and a clear acceptable use policy.

Accountability

Audit logs for important actions and team roles so everyone has only the access they need.

Plans

Start free and move up when you need more. Limits shown are the current plan limits.

Starter

Free

  • 200 emails a day
  • 3,000 emails a month
  • 2 sending domains
  • 10 mailboxes
  • 3 API keys, 2 webhooks
  • Attachments up to 10 MB
  • Open and click tracking
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Business

By arrangement

  • 20,000 emails a day
  • 300,000 emails a month
  • 10 sending domains
  • 10 mailboxes
  • 20 API keys, 10 webhooks
  • Attachments up to 25 MB
  • Open and click tracking
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Enterprise

By arrangement

  • 200,000 emails a day
  • 3M emails a month
  • 50 sending domains
  • 10 mailboxes
  • 100 API keys, 50 webhooks
  • Attachments up to 40 MB
  • Open and click tracking
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Questions

What can I send with mxsin?

Transactional mail such as receipts, sign-ins and notifications, and permission-based marketing to contacts who opted in.

Do I need my own domain?

Yes. You send from your own domain, signed with your own DKIM key, so recipients see your brand.

Can I receive email too?

Yes. Mail to your domain can be posted to your app as JSON, forwarded, or delivered to hosted mailboxes.

Do mailboxes work on phones and desktop apps?

Yes. Standard IMAP and SMTP work with any mail app, and auto-setup records and Apple profiles make setup quick.

How do I get started?

Request access and we will set up your account. The Starter plan is free.

Ready to send with confidence?

Request access today, or talk to us about what you need.

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