Lettermint

Send transactional email one at a time or in batches of up to 500, follow each message's delivery events, read sending statistics, and manage sending domains, webhooks and the suppression list.

Actions

Action	What it does
Add suppressions	Stop Lettermint sending to up to 1,000 addresses, for the whole team or one project.
Create domain	Add a sending domain.
Create webhook	Have Lettermint call a URL when messages are delivered, bounce, are opened and so on.
Delete domain	Remove a sending domain from Lettermint.
Delete webhook	Delete a webhook and its delivery history.
Get domain	Get a sending domain with the DNS records to publish and each record's verification status.
Get message	Get one message: its status, sender, recipients, tags, metadata, attachments and spam score.
Get sending statistics	Get totals and a day-by-day count of emails sent, delivered, bounced, complained about, opened and clicked, for up to 90 days.
Get webhook	Get a webhook's URL, events, scope and status.
List domains	List sending domains and their verification status.
List message events	List a message's delivery timeline: queued, delivered, bounced, opened, clicked and so on, with timestamps.
List messages	List sent and received messages, newest first, filtered by status, sender, subject, tag, project, domain or date.
List projects	List the team's projects with their message volumes and deliverability over the last 28 days.
List suppressions	List the addresses Lettermint will not send to - bounces, spam complaints, unsubscribes and manual blocks.
List webhooks	List webhooks with their URL, events and status.
Remove suppression	Let Lettermint send to a suppressed address again.
Send batch emails	Send up to 500 emails in one request: either the same email to each recipient separately, or a list of different emails.
Send email	Send one email to up to 50 recipients, with an optional attachment, tags and metadata.
Update webhook	Change a webhook's name, URL, events, scope or status.
Verify domain DNS records	Check a domain's DNS records now.

Add suppressions

Stop Lettermint sending to up to 1,000 addresses, for the whole team or one project. Addresses already suppressed are skipped.

Inputs

AddressesemailslistRequired: The addresses to suppress.
Reasonreasontext: Why they are suppressed.One of: manual (Added manually), unsubscribe, hard_bounce (Hard bounce), spam_complaint (Spam complaint). Default: manual.
Applies acrossscopetext: The whole team, one project, or one route.One of: team (Whole team), project (One project), route (One route). Default: team.
Projectproject_idtext: The project to suppress them in.Only when Applies across is One project.
Route IDroute_idtext: The id of the route to suppress them in.Only when Applies across is One route.
Blockapplies_totext: All email, or only broadcasts (transactional email still goes through).One of: all (All email), broadcast (Broadcasts only).

Outputs

createdlist
created_countnumber
messagetext
skippedlist
skipped_countnumber

Example output

{
  "created": [
    "blocked@example.com"
  ],
  "created_count": 1,
  "message": "Suppression processed.",
  "skipped": [],
  "skipped_count": 0
}

Create domain

Add a sending domain. Returns the DNS records to publish at your DNS provider before verifying it. The Free plan allows one domain.

Inputs

DomaindomaintextRequired: The domain to send from, e.g. mail.example.com.

Outputs

created_attext
dkim_modetext
dns_recordslist
domaintext
idtext
projectslist
rotation_readytrue/false
status_changed_attext

Example output

{
  "created_at": "2026-10-01T09:30:00.000000Z",
  "dkim_mode": "managed_cname",
  "dns_records": [
    {
      "content": "lm1._domainkey.lettermint.co",
      "fqdn": "lm1._domainkey.example.com",
      "hostname": "lm1._domainkey",
      "id": "1d2e3f4a-5b6c-4d7e-8f9a-0b1c2d3e4f5a",
      "last_checked_at": null,
      "purpose": "dkim_primary",
      "required_for_verification": true,
      "status": "pending",
      "type": "CNAME",
      "verification_scope": "required",
      "verified_at": null
    }
  ],
  "domain": "example.com",
  "id": "3c4d5e6f-7a8b-4c9d-8e0f-1a2b3c4d5e6f",
  "projects": [
    {
      "id": "9a1f3c2e-4b5d-4e6f-8a7b-1c2d3e4f5a6b",
      "name": "Production"
    }
  ],
  "rotation_ready": false,
  "status_changed_at": null
}

Create webhook

Have Lettermint call a URL when messages are delivered, bounce, are opened and so on. Returns the signing secret - the only time Lettermint shows it.

Inputs

NamenametextRequired: A name to recognise it by.
URLurltextRequired: The address Lettermint calls, e.g. https://example.com/hooks/lettermint.
EventseventstextRequired: The events that call the URL.One or more of: message.created (Message created), message.sent (Message sent), message.delivered (Message delivered), message.auto_replied (Message auto-replied), message.hard_bounced (Message hard bounced), message.soft_bounced (Message soft bounced), message.spam_complaint (Spam complaint), message.failed (Message failed), message.suppressed (Message suppressed), message.unsubscribed (Recipient unsubscribed), and 11 more.
Enabledenabledtrue/false: Start sending events straight away.Default: true.
Include machine eventsinclude_machine_eventstrue/false: Also send opens and clicks made by mail scanners and proxies.
Messagesdelivery_mode_filtertext: Live messages, sandbox messages, or both.One of: live (Live messages), sandbox (Sandbox messages), both.
Applies toscopetext: Events from the whole team, chosen projects, or chosen routes. Defaults to the whole team.One of: team (Whole team), project (Chosen projects), route (Chosen routes).
Projectsproject_idstext: The projects whose events it receives.Only when Applies to is Chosen projects.
Route IDsroute_idslist: The ids of the routes whose events it receives.Only when Applies to is Chosen routes.
Basic auth usernamebasic_auth_usernametext: If your endpoint needs HTTP basic auth.
Basic auth passwordbasic_auth_passwordtext: The password for that username.

Outputs

created_attext
delivery_mode_filtertext
enabledtrue/false
eventslist
has_basic_authtrue/false
idtext
include_machine_eventstrue/false
last_called_attext
messagetext
nametext
project_idslist
route_idslist
scopetext
secrettext
updated_attext
urltext

Example output

{
  "created_at": "2026-10-01T09:30:00.000000Z",
  "delivery_mode_filter": "live",
  "enabled": true,
  "events": [
    "message.delivered",
    "message.hard_bounced"
  ],
  "has_basic_auth": false,
  "id": "5e6f7a8b-9c0d-4e1f-a2b3-c4d5e6f7a8b9",
  "include_machine_events": false,
  "last_called_at": null,
  "message": "Webhook created.",
  "name": "Delivery events",
  "project_ids": [],
  "route_ids": [],
  "scope": "team",
  "secret": "whsec_7f3a9c1e5b2d4f6a8c0e",
  "updated_at": "2026-10-01T09:30:00.000000Z",
  "url": "https://example.com/hooks/lettermint"
}

Delete domain

Remove a sending domain from Lettermint.

Inputs

Domaindomain_idtextRequired: The sending domain. Pick one, or paste its id.

Outputs

deletedtrue/false
domain_idtext
messagetext

Example output

{
  "deleted": true,
  "domain_id": "3c4d5e6f-7a8b-4c9d-8e0f-1a2b3c4d5e6f",
  "message": "Domain deleted."
}

Delete webhook

Delete a webhook and its delivery history.

Inputs

Webhookwebhook_idtextRequired: The webhook. Pick one, or paste its id.

Outputs

deletedtrue/false
messagetext
webhook_idtext

Example output

{
  "deleted": true,
  "message": "Webhook deleted.",
  "webhook_id": "5e6f7a8b-9c0d-4e1f-a2b3-c4d5e6f7a8b9"
}

Get domain

Get a sending domain with the DNS records to publish and each record's verification status.

Inputs

Domaindomain_idtextRequired: The sending domain. Pick one, or paste its id.
Include DNS recordsinclude_dns_recordstrue/false: Return the DNS records and their status.Default: true.
Include projectsinclude_projectstrue/false: Return the projects that use the domain.Default: true.

Outputs

created_attext
dkim_modetext
dns_recordslist
domaintext
idtext
projectslist
rotation_readytrue/false
status_changed_attext

Example output

{
  "created_at": "2026-10-01T09:30:00.000000Z",
  "dkim_mode": "managed_cname",
  "dns_records": [
    {
      "content": "lm1._domainkey.lettermint.co",
      "fqdn": "lm1._domainkey.example.com",
      "hostname": "lm1._domainkey",
      "id": "1d2e3f4a-5b6c-4d7e-8f9a-0b1c2d3e4f5a",
      "last_checked_at": null,
      "purpose": "dkim_primary",
      "required_for_verification": true,
      "status": "pending",
      "type": "CNAME",
      "verification_scope": "required",
      "verified_at": null
    }
  ],
  "domain": "example.com",
  "id": "3c4d5e6f-7a8b-4c9d-8e0f-1a2b3c4d5e6f",
  "projects": [
    {
      "id": "9a1f3c2e-4b5d-4e6f-8a7b-1c2d3e4f5a6b",
      "name": "Production"
    }
  ],
  "rotation_ready": false,
  "status_changed_at": null
}

Get message

Get one message: its status, sender, recipients, tags, metadata, attachments and spam score.

Inputs

Message IDmessage_idtextRequired: The message's id, as returned by Send email or List messages, or copied from the message's page in Lettermint.

Outputs

attachmentslist
bcclist
cclist
created_attext
delivery_modetext
from_emailtext
from_nametext
idtext
metadataobject
reply_tolist
route_idtext
sandbox_resulttext
scheduled_attext
spam_scorenumber
spam_symbolslist
statustext
status_changed_attext
subjecttext
tagtext
tagslist
tolist
typetext

Example output

{
  "attachments": [],
  "bcc": null,
  "cc": null,
  "created_at": "2026-10-01T09:30:00.000000Z",
  "delivery_mode": "live",
  "from_email": "onboarding@lettermint.dev",
  "from_name": "Acme",
  "id": "0b1c2d3e-4f5a-4b6c-9d7e-8f9a0b1c2d3e",
  "metadata": {
    "order_id": "1001"
  },
  "reply_to": null,
  "route_id": "2f3e4d5c-6b7a-4980-a1b2-c3d4e5f6a7b8",
  "sandbox_result": null,
  "scheduled_at": null,
  "spam_score": 0.4,
  "spam_symbols": [],
  "status": "delivered",
  "status_changed_at": "2026-10-01T09:30:04.000000Z",
  "subject": "Your receipt",
  "tag": "receipts",
  "tags": [
    {
      "name": "__lettermint_tag",
      "value": "receipts"
    }
  ],
  "to": [
    {
      "email": "ok@lettermint.dev",
      "name": null,
      "sandbox_result": null
    }
  ],
  "type": "outbound"
}

Get sending statistics

Get totals and a day-by-day count of emails sent, delivered, bounced, complained about, opened and clicked, for up to 90 days. Defaults to the last 7 days.

Inputs

Fromfrom_datedate: First day. Defaults to 6 days before To.
Toto_datedate: Last day. Defaults to today (UTC).
Projectproject_idtext: Only this project - adds a transactional/broadcast breakdown. Pick one, or paste its id.
Include machine opens and clicksinclude_machinetrue/false: Count opens and clicks made by mail scanners too.

Outputs

dailylist
fromtext
totext
totalsobject

Example output

{
  "daily": [
    {
      "broadcast": null,
      "clicked": null,
      "date": "2026-10-01",
      "delivered": 12,
      "effective_opened": null,
      "hard_bounced": 0,
      "human_opened": null,
      "inbound": {
        "received": 0
      },
      "machine_clicked": null,
      "machine_opened": null,
      "observed_opened": null,
      "opened": null,
      "privacy_opened": null,
      "sent": 12,
      "spam_complaints": 0,
      "transactional": null
    }
  ],
  "from": "2026-10-01",
  "to": "2026-10-07",
  "totals": {
    "broadcast": null,
    "clicked": null,
    "delivered": 12,
    "effective_opened": null,
    "hard_bounced": 0,
    "human_opened": null,
    "inbound": {
      "received": 0
    },
    "machine_clicked": null,
    "machine_opened": null,
    "observed_opened": null,
    "opened": null,
    "privacy_opened": null,
    "sent": 12,
    "spam_complaints": 0,
    "transactional": null
  }
}

Get webhook

Get a webhook's URL, events, scope and status.

Inputs

Webhookwebhook_idtextRequired: The webhook. Pick one, or paste its id.

Outputs

created_attext
delivery_mode_filtertext
enabledtrue/false
eventslist
has_basic_authtrue/false
idtext
include_machine_eventstrue/false
last_called_attext
nametext
project_idslist
route_idslist
scopetext
updated_attext
urltext

Example output

{
  "created_at": "2026-10-01T09:30:00.000000Z",
  "delivery_mode_filter": "live",
  "enabled": true,
  "events": [
    "message.delivered",
    "message.hard_bounced"
  ],
  "has_basic_auth": false,
  "id": "5e6f7a8b-9c0d-4e1f-a2b3-c4d5e6f7a8b9",
  "include_machine_events": false,
  "last_called_at": null,
  "name": "Delivery events",
  "project_ids": [],
  "route_ids": [],
  "scope": "team",
  "updated_at": "2026-10-01T09:30:00.000000Z",
  "url": "https://example.com/hooks/lettermint"
}

List domains

List sending domains and their verification status.

Inputs

Domain containsdomaintext: Part of the domain name.
Statusstatustext: Only domains in this verification status.One of: verified, partially_verified (Partially verified), pending_verification (Pending verification), failed_verification (Failed verification).
Projectproject_idtext: Only this project. Pick one, or paste its id.
Sort bysorttext: How to order the domains.One of: domain (Domain A-Z), -created_at (Newest first), created_at (Oldest first), -status_changed_at (Most recent status change first).
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
domainslist
has_moretrue/false
next_cursortext

Example output

{
  "count": 1,
  "domains": [
    {
      "created_at": "2026-10-01T09:30:00.000000Z",
      "dkim_mode": "managed_cname",
      "domain": "example.com",
      "id": "3c4d5e6f-7a8b-4c9d-8e0f-1a2b3c4d5e6f",
      "status": "verified",
      "status_changed_at": "2026-10-01T09:30:00.000000Z"
    }
  ],
  "has_more": false,
  "next_cursor": null
}

List message events

List a message's delivery timeline: queued, delivered, bounced, opened, clicked and so on, with timestamps.

Inputs

Message IDmessage_idtextRequired: The message's id, as returned by Send email or List messages, or copied from the message's page in Lettermint.
Include machine eventsinclude_machine_eventstrue/false: Also list opens and clicks made by mail scanners and proxies.
Ordersorttext: Oldest or newest event first.One of: timestamp (Oldest first), -timestamp (Newest first).
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
eventslist
has_moretrue/false
next_cursortext

Example output

{
  "count": 1,
  "events": [
    {
      "event": "delivered",
      "message_id": "0b1c2d3e-4f5a-4b6c-9d7e-8f9a0b1c2d3e",
      "metadata": null,
      "tag": "receipts",
      "tags": [],
      "timestamp": "2026-10-01T09:30:04.000000Z"
    }
  ],
  "has_more": false,
  "next_cursor": null
}

List messages

List sent and received messages, newest first, filtered by status, sender, subject, tag, project, domain or date.

Inputs

Searchsearchtext: Find messages by address or subject.
Statusstatustext: Only messages in this status.One of: scheduled, pending, queued, quarantined, suppressed, processed, delivered, opened, clicked, soft_bounced (Soft bounced), and 7 more.
Directionmessage_typetext: Only sent or only received messages.One of: outbound (Outbound (sent)), inbound (Inbound (received)).
Sender containsfrom_emailtext: Part of the sender address.
Subject containssubjecttext: Part of the subject.
Tagtagtext: Only messages with exactly this tag. Use _none for untagged.
Tag pairstagsobject: Only messages carrying every one of these name/value tags.
Projectproject_idtext: Only this project. Pick one, or paste its id.
Domaindomain_idtext: Only messages sent from this domain.
Created on or afterfrom_datedate: Earliest creation date.
Created on or beforeto_datedate: Latest creation date.
Sort bysorttext: How to order the messages.One of: -created_at (Newest first), created_at (Oldest first), -status_changed_at (Most recent status change first), subject (Subject A-Z), from_email (Sender A-Z), status (Status A-Z). Default: -created_at.
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
has_moretrue/false
messageslist
next_cursortext

Example output

{
  "count": 1,
  "has_more": false,
  "messages": [
    {
      "bcc": null,
      "cc": null,
      "created_at": "2026-10-01T09:30:00.000000Z",
      "delivery_mode": "live",
      "from_email": "onboarding@lettermint.dev",
      "from_name": "Acme",
      "id": "0b1c2d3e-4f5a-4b6c-9d7e-8f9a0b1c2d3e",
      "reply_to": null,
      "sandbox_result": null,
      "scheduled_at": null,
      "spam_score": 0.4,
      "status": "delivered",
      "status_changed_at": "2026-10-01T09:30:04.000000Z",
      "subject": "Your receipt",
      "tag": "receipts",
      "tags": [
        {
          "name": "__lettermint_tag",
          "value": "receipts"
        }
      ],
      "to": [
        {
          "email": "ok@lettermint.dev",
          "name": null,
          "sandbox_result": null
        }
      ],
      "type": "outbound"
    }
  ],
  "next_cursor": null
}

List projects

List the team's projects with their message volumes and deliverability over the last 28 days.

Inputs

Searchsearchtext: Find projects by name.
Sort bysorttext: How to order the projects.One of: name (Name A-Z), -created_at (Newest first), created_at (Oldest first).
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
has_moretrue/false
next_cursortext
projectslist

Example output

{
  "count": 1,
  "has_more": false,
  "next_cursor": null,
  "projects": [
    {
      "created_at": "2026-10-01T09:30:00.000000Z",
      "delivery_mode": "live",
      "domains_count": 1,
      "id": "9a1f3c2e-4b5d-4e6f-8a7b-1c2d3e4f5a6b",
      "last_28_days": {
        "deliverability": 99.2,
        "messages_broadcast": 0,
        "messages_inbound": 0,
        "messages_transactional": 120
      },
      "name": "Production",
      "routes_count": 2,
      "smtp_enabled": false,
      "updated_at": "2026-10-01T09:30:00.000000Z"
    }
  ]
}

List suppressions

List the addresses Lettermint will not send to - bounces, spam complaints, unsubscribes and manual blocks.

Inputs

Address containsvaluetext: Part of the address.
Reasonreasontext: Only suppressions for this reason.One of: spam_complaint (Spam complaint), hard_bounce (Hard bounce), unsubscribe, manual (Added manually), disposable_email (Disposable email).
Scopescopetext: Only suppressions at this level.One of: team (Whole team), project (One project), route (One route).
Projectproject_idtext: Only this project. Pick one, or paste its id.
Added on or afterstart_datedate: Earliest date.
Added on or beforeend_datedate: Latest date.
Sort bysorttext: How to order the suppressions.One of: -created_at (Newest first), created_at (Oldest first), value (Address A-Z), reason (Reason A-Z). Default: -created_at.
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
has_moretrue/false
next_cursortext
suppressionslist

Example output

{
  "count": 1,
  "has_more": false,
  "next_cursor": null,
  "suppressions": [
    {
      "applies_to": "all",
      "created_at": "2026-10-01T09:30:00.000000Z",
      "id": "7a8b9c0d-1e2f-4a3b-8c4d-5e6f7a8b9c0d",
      "project_id": null,
      "reason": "hard_bounce",
      "route_id": null,
      "scope": "team",
      "source_message": null,
      "type": "email",
      "value": "bounced@example.com"
    }
  ]
}

List webhooks

List webhooks with their URL, events and status.

Inputs

Searchsearchtext: Find webhooks by name or URL.
Statusenabledtext: Only enabled or only disabled webhooks.One of: enabled, disabled.
Eventeventtext: Only webhooks that receive this event.One of: message.created (Message created), message.sent (Message sent), message.delivered (Message delivered), message.auto_replied (Message auto-replied), message.hard_bounced (Message hard bounced), message.soft_bounced (Message soft bounced), message.spam_complaint (Spam complaint), message.failed (Message failed), message.suppressed (Message suppressed), message.unsubscribed (Recipient unsubscribed), and 11 more.
Scopescopetext: Only webhooks at this level.One of: team (Whole team), project (Chosen projects), route (Chosen routes).
Projectproject_idtext: Only this project. Pick one, or paste its id.
Sort bysorttext: How to order the webhooks.One of: -created_at (Newest first), created_at (Oldest first), name (Name A-Z), url (URL A-Z).
Page sizepage_sizenumber: How many to return on this page.From 1 to 100.
Page cursorcursortext: The next_cursor from a previous page. Leave empty for the first page.

Outputs

countnumber
has_moretrue/false
next_cursortext
webhookslist

Example output

{
  "count": 1,
  "has_more": false,
  "next_cursor": null,
  "webhooks": [
    {
      "created_at": "2026-10-01T09:30:00.000000Z",
      "delivery_mode_filter": "live",
      "enabled": true,
      "events": [
        "message.delivered",
        "message.hard_bounced"
      ],
      "has_basic_auth": false,
      "id": "5e6f7a8b-9c0d-4e1f-a2b3-c4d5e6f7a8b9",
      "last_called_at": null,
      "name": "Delivery events",
      "project_ids": [],
      "route_ids": [],
      "scope": "team",
      "updated_at": "2026-10-01T09:30:00.000000Z",
      "url": "https://example.com/hooks/lettermint"
    }
  ]
}

Remove suppression

Let Lettermint send to a suppressed address again. A spam complaint is sent to Lettermint support for review instead of being removed - removed tells you which happened.

Inputs

Suppression IDsuppression_idtextRequired: The suppression's id, from List suppressions.

Outputs

messagetext
removedtrue/false
statustext
suppression_idtext
ticket_identifiertext

Example output

{
  "message": "Suppression removed.",
  "removed": true,
  "status": "removed",
  "suppression_id": "7a8b9c0d-1e2f-4a3b-8c4d-5e6f7a8b9c0d",
  "ticket_identifier": null
}

Send batch emails

Send up to 500 emails in one request: either the same email to each recipient separately, or a list of different emails. Returns one message id per email, in order.

Inputs

Recipientsrecipientslist: Send the email below to each of these addresses separately (they do not see each other).
Fromsendertext: The sender, as an address or Name <address>, on a domain verified in Lettermint. Until you verify one, use Your App <onboarding@lettermint.dev>, which can send to your team's verified members and test addresses such as ok@lettermint.dev.
Subjectsubjecttext: The subject line.
HTML bodyhtmltext: The email as HTML. Give this, a text body, or both.
Text bodytexttext: The plain-text version. Give this, an HTML body, or both.
Tagtagtext: A label to find these emails by later (letters, digits, - and _), e.g. password-reset.
Emails (advanced)emailslist: A list of email objects, each with from, to, subject and html and/or text, plus any of cc, bcc, reply_to, tag, tags, metadata, headers, route and scheduled_at - e.g. [{"from": "Acme <hello@acme.com>", "to": ["a@example.com"], "subject": "Hi", "text": "Hello there"}]. Leave empty to send one email to each recipient below instead.
Idempotency keyidempotency_keytext: Optional. Lettermint ignores a repeat with the same key and body for 24 hours, so a retried step cannot send twice. Use something unique to this email, such as an order id.

Outputs

countnumber
messageslist

Example output

{
  "count": 1,
  "messages": [
    {
      "message_id": "0b1c2d3e-4f5a-4b6c-9d7e-8f9a0b1c2d3e",
      "status": "pending"
    }
  ]
}

Send email

Send one email to up to 50 recipients, with an optional attachment, tags and metadata. Returns the message id to follow its delivery.

Inputs

FromsendertextRequired: The sender, as an address or Name <address>, on a domain verified in Lettermint. Until you verify one, use Your App <onboarding@lettermint.dev>, which can send to your team's verified members and test addresses such as ok@lettermint.dev.
TotolistRequired: One or more recipients, as addresses or Name <address>.
SubjectsubjecttextRequired: The subject line.
HTML bodyhtmltext: The email as HTML. Give this, a text body, or both.
Text bodytexttext: The plain-text version. Give this, an HTML body, or both.
Cccclist: Copy these recipients.
Bccbcclist: Blind-copy these recipients.
Reply toreply_tolist: Where replies should go.
Attachmentattachmenttext: A file to attach.
Attachment file nameattachment_nametext: The name the recipient sees, e.g. invoice.pdf. Defaults to the uploaded file's name.
Tagtagtext: A label to find these emails by later (letters, digits, - and _), e.g. password-reset.
Tag pairstagsobject: Name/value tags to filter by later, e.g. plan = pro (each 1-32 / 1-64 letters, digits, - or _).
Metadatametadataobject: Your own values stored with the message and sent to your webhooks, not added to the email.
Custom headersheadersobject: Extra email headers, e.g. X-Campaign = autumn.
Routeroutetext: The route slug to send through. Leave empty for the project's default route.
Send atscheduled_atdate and time: Deliver later instead of now. Scheduling needs a Lettermint Growth or Pro plan.
Track openstrack_openstrue/false: Track when the email is opened (paid plans).
Track clickstrack_clickstrue/false: Track clicks on links (paid plans).
TLS policytlstext: Whether delivery must use an encrypted connection.One of: opportunistic (Opportunistic (use TLS when the receiver offers it)), enforced (Enforced (do not deliver without TLS)).
Idempotency keyidempotency_keytext: Optional. Lettermint ignores a repeat with the same key and body for 24 hours, so a retried step cannot send twice. Use something unique to this email, such as an order id.

Outputs

message_idtext
scheduled_attext
statustext

Example output

{
  "message_id": "0b1c2d3e-4f5a-4b6c-9d7e-8f9a0b1c2d3e",
  "status": "pending"
}

Update webhook

Change a webhook's name, URL, events, scope or status. Fields left empty are not changed.

Inputs

Webhookwebhook_idtextRequired: The webhook. Pick one, or paste its id.
Namenametext: A new name.
URLurltext: A new address for Lettermint to call.
Eventseventstext: Replace the events it receives.One or more of: message.created (Message created), message.sent (Message sent), message.delivered (Message delivered), message.auto_replied (Message auto-replied), message.hard_bounced (Message hard bounced), message.soft_bounced (Message soft bounced), message.spam_complaint (Spam complaint), message.failed (Message failed), message.suppressed (Message suppressed), message.unsubscribed (Recipient unsubscribed), and 11 more.
Statusenabledtext: Turn the webhook on or off.One of: enabled, disabled.
Machine eventsinclude_machine_eventstext: Send opens and clicks made by mail scanners and proxies, or not.One of: enabled, disabled.
Messagesdelivery_mode_filtertext: Live messages, sandbox messages, or both.One of: live (Live messages), sandbox (Sandbox messages), both.
Applies toscopetext: Events from the whole team, chosen projects, or chosen routes.One of: team (Whole team), project (Chosen projects), route (Chosen routes).
Projectsproject_idstext: The projects whose events it receives.Only when Applies to is Chosen projects.
Route IDsroute_idslist: The ids of the routes whose events it receives.Only when Applies to is Chosen routes.
Basic auth usernamebasic_auth_usernametext: Set new HTTP basic auth credentials.
Basic auth passwordbasic_auth_passwordtext: The password for that username.
Remove basic authremove_basic_authtrue/false: Stop sending basic auth credentials.

Outputs

created_attext
delivery_mode_filtertext
enabledtrue/false
eventslist
has_basic_authtrue/false
idtext
include_machine_eventstrue/false
last_called_attext
messagetext
nametext
project_idslist
route_idslist
scopetext
updated_attext
urltext

Example output

{
  "created_at": "2026-10-01T09:30:00.000000Z",
  "delivery_mode_filter": "live",
  "enabled": true,
  "events": [
    "message.delivered",
    "message.hard_bounced"
  ],
  "has_basic_auth": false,
  "id": "5e6f7a8b-9c0d-4e1f-a2b3-c4d5e6f7a8b9",
  "include_machine_events": false,
  "last_called_at": null,
  "message": "Webhook updated.",
  "name": "Delivery events",
  "project_ids": [],
  "route_ids": [],
  "scope": "team",
  "updated_at": "2026-10-01T09:30:00.000000Z",
  "url": "https://example.com/hooks/lettermint"
}

Verify domain DNS records

Check a domain's DNS records now. Returns verified true or false, with the records that still fail. Lettermint allows only a few checks a minute.

Inputs

Domaindomain_idtextRequired: The sending domain. Pick one, or paste its id.

Outputs

domain_idtext
errorslist
failed_countnumber
failed_recordslist
messagetext
recommended_failed_recordslist
total_countnumber
verifiedtrue/false

Example output

{
  "domain_id": "3c4d5e6f-7a8b-4c9d-8e0f-1a2b3c4d5e6f",
  "errors": [
    {
      "error": "Record not found.",
      "record_id": "1d2e3f4a-5b6c-4d7e-8f9a-0b1c2d3e4f5a"
    }
  ],
  "failed_count": 1,
  "failed_records": [
    {
      "id": "1d2e3f4a-5b6c-4d7e-8f9a-0b1c2d3e4f5a",
      "name": "lm1._domainkey",
      "type": "CNAME"
    }
  ],
  "message": "Some required DNS records could not be verified.",
  "recommended_failed_records": [],
  "total_count": 4,
  "verified": false
}

ActionsCopy Anchor Link

Add suppressionsCopy Anchor Link

Inputs

Outputs

Create domainCopy Anchor Link

Inputs

Outputs

Create webhookCopy Anchor Link

Inputs

Outputs

Delete domainCopy Anchor Link

Inputs

Outputs

Delete webhookCopy Anchor Link

Inputs

Outputs

Get domainCopy Anchor Link

Inputs

Outputs

Get messageCopy Anchor Link

Inputs

Outputs

Get sending statisticsCopy Anchor Link

Inputs

Outputs

Get webhookCopy Anchor Link

Inputs

Outputs

List domainsCopy Anchor Link

Inputs

Outputs

List message eventsCopy Anchor Link

Inputs

Outputs

List messagesCopy Anchor Link

Inputs

Outputs

List projectsCopy Anchor Link

Inputs

Outputs

List suppressionsCopy Anchor Link

Inputs

Outputs

List webhooksCopy Anchor Link

Inputs

Outputs

Remove suppressionCopy Anchor Link

Inputs

Outputs

Send batch emailsCopy Anchor Link

Inputs

Outputs

Send emailCopy Anchor Link

Inputs

Outputs

Update webhookCopy Anchor Link

Inputs

Outputs

Verify domain DNS recordsCopy Anchor Link

Inputs

Outputs

On this page

Actions

Add suppressions

Create domain

Create webhook

Delete domain

Delete webhook

Get domain

Get message

Get sending statistics

Get webhook

List domains

List message events

List messages

List projects

List suppressions

List webhooks

Remove suppression

Send batch emails

Send email

Update webhook

Verify domain DNS records