Sendinblue offers two options to add an attachment to a transactional email:
The size limit for transactional emails is 10MB (including the attachment and email content). If your transactional email exceeds this size limit, we recommend that you host your file elsewhere (such as Dropbox), provide public access to the hosted file, and share the link to it in your email template. Doing so would ensure that your link is valid and that your file can be downloaded by the recipients.
Allowed extensions for attachment file: 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, and wmv.
Add the attachment in your email template setup
At the Setup step of your email template, select a file in the Add an attachment field.
Include the attachment in your API script
Using our API v3, include either a file you are hosting or the base64 content of the attachment in your API script.
To learn how to include an attachment in a transactional email using our API v3, refer to our technical documentation.