Array of attachment objects. Each attachment must include either an absolute URL (no local file paths) or base64-encoded content, along with the attachment filename. The name field is required when content is provided. Supported file extensions: xlsx, xls, ods, docx, docm, doc, csv, pdf, txt, gif, jpg, jpeg, png, tif, tiff, rtf, bmp, cgm, css, shtml, html, htm, zip, xml, ppt, pptx, tar, ez, ics, mobi, msg, pub, eps, odt, mp3, m4a, m4v, wma, ogg, flac, wav, aif, aifc, aiff, mp4, mov, avi, mkv, mpeg, mpg, wmv, pkpass, xlsm. When templateId is specified: if the template uses the New Template Language format, both url and content attachment types are supported; if the template uses the Old Template Language format, the attachment parameter is ignored.

Array of BCC recipient objects. Each object contains an email address and an optional name.

Array of CC recipient objects. Each object contains an email address and an optional name.

Custom email headers (non-standard headers) to include in the email. The sender.ip header can be set to specify the IP address used for sending transactional emails (dedicated IP users only). Header names must use Title-Case-Format (words separated by hyphens with the first letter of each word capitalized). Headers not in this format are automatically converted. Standard email headers are not supported. Example: {"sender.ip":"1.2.3.4", "X-Mailin-custom":"some_custom_value", "Idempotency-Key":"abc-123"}

Array of message version objects for sending customized email variants. The templateId can be customized per version only if a global templateId is provided. The htmlContent and textContent can be customized per version only if at least one of these is present in the global parameters. Global parameters such as to (required), bcc, cc, replyTo, and subject can be customized per version. Maximum total recipients per API request is 2000. Maximum recipients per message version is 99. Individual params objects must not exceed 100 KB. Cumulative params across all versions must not exceed 1000 KB. See https://developers.brevo.com/docs/batch-send-transactional-emails for detailed usage instructions.

Key-value pairs for template variable substitution. Only applicable when the template uses the New Template Language format.

Reply-to email address (required) and optional display name. Recipients will use this address when replying to the email.

Sender information. Required when templateId is not provided. Specify either an email address (with optional name) or a sender ID. The name field is ignored when id is provided.

Array of tags for categorizing and filtering emails

Array of recipient objects. Each object contains an email address and an optional display name. Required when messageVersions is not provided. Ignored when messageVersions is provided. Example: [{"name":"Jimmy", "email":"[email protected]"}, {"name":"Joe", "email":"[email protected]"}]