mailflare/docs/api.md

API and integrations

Mailflare exposes APIs for domain management and sending email. Authentication and mailbox permissions still apply to these routes.

Domain management

Adding or removing a domain from Mailflare also updates Cloudflare Email Routing and sending resources.

Mailflare route	Purpose
GET /api/domains	List connected domains
POST /api/domains	Connect a domain and configure Cloudflare
GET /api/domains/[id]	Get a connected domain
DELETE /api/domains/[id]	Remove a domain and clean up its Cloudflare resources
GET /api/domains/[id]/dns	View its routing and sending DNS status

The hostname must be the apex of a zone available to the configured Cloudflare credentials, or a subdomain of that zone. Creating a mailbox also creates the Cloudflare Email Routing rule that delivers its address to the mailflare Worker.

Sending email

Send email through POST /api/v1/send. to, cc and bcc accept either a comma-separated header string or an array of addresses; each entry may carry a display name ("Maya Chen" <maya@example.net>). A message can reach up to 50 recipients across the three fields. Attachments are optional and use Base64-encoded content:

{
  "from": "support@example.com",
  "to": ["user@example.net", "\"Maya Chen\" <maya@example.net>"],
  "cc": "ops@example.com",
  "bcc": ["audit@example.com"],
  "subject": "Report",
  "text": "Attached.",
  "attachments": [
    {
      "filename": "report.pdf",
      "type": "application/pdf",
      "contentBase64": "<base64 data>"
    }
  ]
}

To send a reply that threads correctly in the recipient's client, pass the parent's Message-ID as inReplyTo and its chain as references (a header string or an array). Mailflare writes the In-Reply-To and References headers, files the sent copy in the same conversation, and stores threadId, inReplyTo and references on every message.

{
  "from": "support@example.com",
  "to": "user@example.net",
  "subject": "Re: Report",
  "text": "Thanks, received.",
  "inReplyTo": "<CAF1abc@mail.example.net>",
  "references": ["<CAF0root@mail.example.net>", "<CAF1abc@mail.example.net>"]
}

GET /api/messages/{id}/thread (session auth) returns every stored message in the same conversation, oldest first, excluding drafts and trash. GET /api/messages?group=thread collapses a list to one row per conversation (its newest message matching the filter) and adds threadCount, threadUnread and threadMessageIds, the ids that row stands for within the current filter, so bulk actions can act on the whole conversation.

Messages composed in Mailflare are sent as HTML with a plain-text alternative derived from it. Quoted or forwarded content is wrapped in <div class="mailflare-quote" data-mailflare-quote="1"> so the reader can fold it. POST /api/drafts accepts forwardOfMessageId, which copies that message's attachments onto the new draft; DELETE /api/drafts/{id}/attachments/{attachmentId} removes one, and POST /api/send with draftId sends the draft's stored files along with any uploaded in the request.

The dashboard composer accepts up to 10 attachments, with a 10 MB limit per file and a 20 MB combined limit. Attachment metadata is stored in D1 and file content is stored in R2. Downloads require access to the mailbox containing the message.

JMAP

Mailflare serves JMAP (RFC 8620 core and RFC 8621 mail, plus submission) so external mail apps can read and send mail. Discovery is at /.well-known/jmap, which redirects to /jmap/session. Authenticate with an API key that has the jmap scope, either as Authorization: Bearer <key> or as the password of HTTP Basic auth (the username is ignored). Settings > Account > Email apps mints such a key.

The account id is the user id. Each Mailflare mailbox appears as a top-level JMAP Mailbox with system children (inbox, drafts, sent, archive, junk, trash) and one child per user folder; a message belongs to exactly one of them. Supported methods: Mailbox/get|query|set (folders only), Thread/get, Email/get|query|set|import, SearchSnippet/get, Identity/get, EmailSubmission/set, and Core/echo. Email/copy and Email/parse are not implemented. */changes return cannotCalculateChanges, so clients re-query on a state change; /jmap/eventsource pushes state changes by polling. Email/set creates drafts, updates $seen and $flagged, moves between mailboxes, and destroys (to Trash first, then permanently). EmailSubmission/set sends a draft and reports it destroyed, since the sent copy is a new message. Blob download and upload follow the Session's downloadUrl and uploadUrl.

Email/import takes a message/rfc822 blob that was uploaded first and stores it as a draft, which is how clients that compose MIME themselves send: upload, import, then EmailSubmission/set. Each entry takes blobId, mailboxIds, and optionally keywords and receivedAt. The target must be exactly one Drafts mailbox — importing into Inbox or a folder is rejected with invalidProperties on mailboxIds, because delivered mail belongs to the inbound pipeline that does threading and spam scoring. $seen and $flagged are stored, $draft is implied, and other keywords are ignored. receivedAt sets the message date, falling back to the Date header and then to now. The uploaded bytes are kept verbatim, so downloading the new message's blobId returns exactly what was uploaded rather than a reconstruction, and the Message-ID header is stored so the client can find its own draft again. Per-message failures come back in notCreated as blobNotFound, invalidEmail, invalidProperties, forbidden (the From address is not one the key may send from) or tooLarge.

Email/query supports the header filter: ["Message-ID", "<id@example.com>"] matches messages with that value, and ["Message-ID"] matches any message that has the header. Message-ID, In-Reply-To and References are answered from stored columns; Message-IDs compare with or without angle brackets, and header names are case-insensitive. Any other header name returns an unsupportedFilter error rather than silently matching everything.

Password reset and two-factor authentication

POST /api/auth/password-reset/request with { email } always answers 200 { ok: true }; when the account exists and has a recovery email, a single-use link valid for 30 minutes is mailed there. POST /api/auth/password-reset/confirm with { token, password } sets the password and signs the account out everywhere.

When two-factor authentication is on, POST /api/auth/login returns { ok: true, mfaRequired: true, challengeToken } instead of a session. POST /api/auth/mfa/verify with { challengeToken, code } completes the sign-in; code is a 6-digit TOTP or one of the recovery codes. Challenges expire after 5 minutes. Enrolment, recovery codes and turning it off are under /api/settings/mfa/* (session auth) and always re-check the password.

Searching

GET /api/messages?q=... (session) and GET /api/v1/messages?q=... (API key, read scope) accept the same query grammar, backed by an FTS5 index over subject, sender, recipients and body:

Syntax	Meaning
invoice	prefix match anywhere (inv finds "invoice")
"private window"	exact phrase
-word	exclude
from:maya, to:sam, subject:report	restrict a term to one field (to: covers Cc)
has:attachment	at least one non-inline attachment
is:unread, is:read, is:starred	flags
after:2026-09-01, before:2026-09-30	date bounds (UTC, before exclusive)

Terms combine with AND. Admins can check or rebuild the index with GET / POST /api/admin/search-index; triggers keep it current, so a rebuild is only needed after restoring a backup made before the index existed.

Real-time updates

Mailflare uses a Durable Object WebSocket hub to notify connected users after an inbound message is stored. Mailbox owners, the domain administrator, and delegated users receive events for mailboxes they can access.

The REALTIME binding and its migration are declared in wrangler.jsonc. When a WebSocket is temporarily unavailable, the app retries the connection and uses a slower refresh until it recovers.