Template Object

Creates a Template object for sending template-based emails via the Postmark API. This provides a structured way to send emails using predefined Postmark templates. It supports:

Template variable substitution via template_model
Multiple recipients via To, Cc, and Bcc fields (max 50 combined)
Inline CSS processing for better email client compatibility
Open and click tracking configuration
Email categorization via tags
File attachments and custom headers
Metadata for internal tracking

Usage

template(
  template_model,
  from = character(0),
  to = character(0),
  id = numeric(0),
  alias = character(0),
  cc = character(0),
  bcc = character(0),
  inline_css = logical(0),
  tag = character(0),
  reply_to = character(0),
  headers = list(),
  track_opens = logical(0),
  track_links = character(0),
  attachments = list(),
  metadata = list()
)

Template(
  from = character(0),
  to = character(0),
  id = integer(0),
  alias = character(0),
  template_model = list(),
  cc = character(0),
  bcc = character(0),
  inline_css = logical(0),
  tag = character(0),
  reply_to = character(0),
  headers = list(),
  track_opens = logical(0),
  track_links = character(0),
  attachments = list(),
  metadata = list()
)

Arguments

template_model: List. Required. Named list of variables to populate in the template. Keys must match template variable names. Can include nested lists for complex data structures. If the template has no placeholders, pass an empty list: list(). Example with variables: list(user_name = "John", company = list(name = "ACME")).
from: Character scalar. Required. Sender email address (must be verified in Postmark). Supports name formatting: "John Doe <email@example.com>"
to: Character vector. Required. Recipient email addresses. Multiple recipients allowed (max 50 total across To, Cc, Bcc)
id: Integer scalar. The template ID in Postmark. Must be a positive integer corresponding to an existing template in your account. Typically an 8-digit number (e.g., 12345678). Mutually exclusive with alias.
alias: Character scalar. The template alias in Postmark. A named identifier for your template (e.g., "welcome-email", "password-reset"). Mutually exclusive with id.
cc: Character vector. Carbon copy recipients. Visible to all recipients.
bcc: Character vector. Blind carbon copy recipients. Hidden from other recipients.
inline_css: Logical scalar. Whether to process CSS in <style> tags into inline style attributes. Improves compatibility with email clients. Default is TRUE for better rendering.
tag: Character scalar. Category tag for statistics and filtering. One tag per message, maximum 1000 characters. Examples: "welcome-email", "password-reset", "invoice".
reply_to: Character scalar. Reply-To address for responses.
headers: List of lists. Custom email headers. Each element should have Name and Value keys. Example: list(list(Name = "X-Priority", Value = "High")). Use for custom routing, priority settings, or Message-ID override.
track_opens: Logical scalar. Enable open tracking using invisible pixel. Only works with HTML emails. Provides insights on when and where emails are opened.
track_links: Character scalar. Link tracking mode. Options: "None" (no tracking), "HtmlAndText" (track all links), "HtmlOnly" (HTML links only), "TextOnly" (text links only). Replaces URLs with tracking URLs that redirect to original destination.
attachments: List of lists. File attachments and inline images. Each attachment should have Name, Content (base64-encoded), ContentType, and optionally ContentID (for inline images) keys. Total message size including attachments limited to 10 MB.
metadata: List. Key-value pairs for internal tracking. Does not affect email delivery. Example: list(customer_id = "12345", campaign = "onboarding").

Limitations

Maximum 50 total recipients (To, Cc, Bcc combined)
Maximum 10 MB total message size (including attachments)
One tag per message, maximum 1000 characters

Examples

if (FALSE) { # \dontrun{
# Simple template email using template ID
simple_template <- template(
  from = "sender@example.com",
  to = "recipient@example.com",
  id = 12345678L,
  template_model = list(name = "John", message = "Welcome!")
)

# Template email using template alias
alias_template <- template(
  from = "sender@example.com",
  to = "recipient@example.com",
  alias = "welcome-email",
  template_model = list(name = "John", message = "Welcome!")
)

# Template with no placeholders (empty model required)
no_placeholders <- template(
  from = "sender@example.com",
  to = "recipient@example.com",
  id = 11111111L,
  template_model = list()
)

# Template with tracking, attachments, and metadata
full_template <- template(
  from = "notifications@example.com",
  to = c("user1@example.com", "user2@example.com"),
  cc = "manager@example.com",
  id = 67890123L,
  template_model = list(
    order_id = "ORD-789",
    status = "Completed"
  ),
  inline_css = TRUE,
  tag = "order-confirmation",
  reply_to = "support@example.com",
  headers = list(
    list(Name = "X-Priority", Value = "High")
  ),
  track_opens = TRUE,
  track_links = "HtmlOnly",
  attachments = list(
    list(
      Name = "invoice.pdf",
      Content = "base64content",
      ContentType = "application/pdf"
    )
  ),
  metadata = list(
    customer_id = "12345",
    order_type = "subscription"
  )
)
} # }

Usage

Arguments

Limitations

See also

Examples