Mailchimp Transactional — Send email

Settings

Setting	What it is
ConnectionRequired	The Mailchimp Transactional connection the step signs in with.
From addressRequired	Must be on a domain you verified in Mailchimp Transactional — mail from an unverified domain comes back refused with the reason unsigned.
From name	text
To	Comma-separated. For a list from an earlier node, write {{ join(trigger.recipients, ", ") }}.
Cc	text
Bcc	text
Subject	text
Attachments	The key is the file name, the value its base64 — Pick file… fills both in. The type is taken from the file's extension; use Attachments (JSON) below to set it yourself. Everything together must stay under 25 MB, and base64 is about a third larger than the file on disk.
Inline images	The key is the content id you reference from the HTML as <img src="cid:the-key">. Only image files: Mailchimp refuses an inline attachment whose type does not start with image/.
Merge values	\|NAME\| in the body is replaced by the value here. A name may not start with an underscore.
Merge language	In Handlebars mode the braces belong to Mailchimp, so a Flowmage expression in the body has to be written with the Fixed/Expression switch rather than inline.
Tags	Comma-separated. Each tag is at most 50 characters and may not start with an underscore; Mailchimp stores only the first 100 distinct tags it sees.
Metadata	Stored with the message and searchable afterwards. Up to 10 fields can be indexed for search in Mailchimp's own settings.
Extra headers	object of text
Subaccount id	Routes the send through a subaccount, which must already exist.
Track opens	"" or "on" or "off"
Track clicks	"" or "on" or "off"
Show every recipient in To	"" or "on" or "off"
Send ahead of other mail	"" or "on" or "off"
Generate a plain-text part	"" or "on" or "off"
Generate an HTML part	"" or "on" or "off"
Inline the CSS	Mailchimp only inlines CSS on HTML under 256 KB.
Strip query strings from tracked links	"" or "on" or "off"
Log the content	Off keeps the message body out of Mailchimp's own activity log, where the Get message content node reads it from.
Bcc every message to	text
Tracking domain	A tracking domain already set up on the account; empty uses the account's own.
Return-path domain	Signing domain is deliberately not offered here: Mailchimp ignores it for every account created on or after 1 December 2015.
Google Analytics domains	Comma-separated. Links to these domains get the campaign parameters added.
Google Analytics campaign	text
Recipients (JSON)	When this is filled in it replaces To, Cc and Bcc — it is the only way to give a recipient a display name.
Per-recipient merge values (JSON)	One entry per recipient, each with the values that recipient's body uses.
Per-recipient metadata (JSON)	Stored with that recipient's copy and searchable afterwards.
Attachments (JSON)	Replaces the Attachments list above when it is filled in — use it when you need to set the type yourself.
Body	"html" or "text" or "both"
HTML body	text
Plain-text body	text
Send at	UTC, as 2026-10-01 09:00:00, at most a year ahead. A time in the past sends immediately, and scheduling needs a positive account balance.
Dedicated IP pool	The name of a dedicated IP pool on the account; empty uses the default pool.
Send in the background	Every recipient comes back as queued and refusals only appear on the reject webhook. Mailchimp forces this on above 10 recipients whatever this says.
Fail when a recipient is refused	Mailchimp answers HTTP 200 even when it refuses a recipient. With this on, the node fails and names the reasons; with it off, the node succeeds and you read rejected from its output.

Technical details

Key	Value
`connection`	texta connection id from `requires.connections` (provider `mailchimp-transactional`)
`fromEmail`	text
`fromName`	text
`to`	text
`cc`	text
`bcc`	text
`subject`	text
`attachments`	object of text, by default `{}`
`images`	object of text, by default `{}`
`globalMergeVars`	object of text, by default `{}`
`mergeLanguage`	"mailchimp" or "handlebars", by default `"mailchimp"`
`tags`	text
`metadata`	object of text, by default `{}`
`headers`	object of text, by default `{}`
`subaccount`	text
`trackOpens`	"" or "on" or "off"
`trackClicks`	"" or "on" or "off"
`preserveRecipients`	"" or "on" or "off"
`important`	"" or "on" or "off"
`autoText`	"" or "on" or "off"
`autoHtml`	"" or "on" or "off"
`inlineCss`	"" or "on" or "off"
`urlStripQs`	"" or "on" or "off"
`viewContentLink`	"" or "on" or "off"
`bccAddress`	text
`trackingDomain`	text
`returnPathDomain`	text
`googleAnalyticsDomains`	text
`googleAnalyticsCampaign`	text
`recipientsJson`	textits `{{ }}` must give an array
`mergeVarsJson`	textits `{{ }}` must give an array
`recipientMetadataJson`	textits `{{ }}` must give an array
`attachmentsJson`	textits `{{ }}` must give an array
`bodyFormat`	"html" or "text" or "both", by default `"html"`
`html`	textused when `bodyFormat` is one of "html", "both"
`text`	textused when `bodyFormat` is one of "text", "both"
`sendAt`	text
`ipPool`	text
`async`	true/false, by default `false`
`failOnReject`	true/false, by default `true`

Output

Field	Type
`results`One entry per recipient	array
`messageIds`	array
`sent`Recipients sent to	number
`queued`Recipients queued	number
`scheduled`Recipients scheduled	number
`rejected`Recipients refused	number
`invalid`Addresses Mailchimp could not read	number
`rejectReasons`Why recipients were refused	array
`queuedReasons`Why recipients were queued	array
`allAccepted`Every recipient was accepted	boolean

Sample output, and the expression for each field

allAcceptedtrue
invalid0
messageIds
- [0]"msg-1"
queued0
queuedReasons[]
rejectReasons[]
rejected0
results
- [0]
  - _id"msg-1"
  - email"jane@example.com"
  - status"sent"
scheduled0
sent1

Errors

When a step of this node stops a run, the run page shows a code. Look it up:

Mailchimp Transactional errors

21 codes

Common errors

93 codes

Example step

The step as a flow file holds it. Replace each value in <…>.

{
  "config": {
    "async": false,
    "attachments": {},
    "attachmentsJson": "",
    "autoHtml": "",
    "autoText": "",
    "bcc": "",
    "bccAddress": "",
    "bodyFormat": "html",
    "cc": "",
    "connection": "<connection id>",
    "failOnReject": true,
    "fromEmail": "<from address>",
    "fromName": "",
    "globalMergeVars": {},
    "googleAnalyticsCampaign": "",
    "googleAnalyticsDomains": "",
    "headers": {},
    "html": "",
    "images": {},
    "important": "",
    "inlineCss": "",
    "ipPool": "",
    "mergeLanguage": "mailchimp",
    "mergeVarsJson": "",
    "metadata": {},
    "preserveRecipients": "",
    "recipientMetadataJson": "",
    "recipientsJson": "",
    "returnPathDomain": "",
    "sendAt": "",
    "subaccount": "",
    "subject": "",
    "tags": "",
    "text": "",
    "to": "",
    "trackClicks": "",
    "trackOpens": "",
    "trackingDomain": "",
    "urlStripQs": "",
    "viewContentLink": ""
  },
  "label": "Send email",
  "type": "mandrill.sendEmail",
  "version": 1
}

Send email

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