type
type: "image/gif" | "image/jpeg" | "image/pjpeg" | "image/jpg" | "image/bmp" | "image/png" | "image/x-png" | "image/tiff" | "image/tif" | "application/pdf" | "application/vnd.ms-excel" | "application/msword" | "application/vnd.ms-powerpoint" | "application/vnd.openxmlformats-officedocument.wordprocessingml.document" | "application/vnd.openxmlformats-officedocument.presentationml.presentation" | "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" | "application/vnd.oasis.opendocument.text" | "text/plain"
The content (Buffer) of the attachment in base64 format.