When an email bounces, the receiving mail server often sends back a “delivery status notification” email. That email is usually multipart MIME, with pieces like:
message/delivery-status: structured delivery failure details, such as failed recipient, SMTP status code, reason.message/rfc822: a copy of the original email or original headers.message/global-headers: header-only metadata.
These parts are not normal user attachments like invoice.pdf or image.png. They are technical sub-parts of the bounce email, and mail providers often expose them through the same attachments API even though they do not have a filename. Nylas returns filename: undefined.
When an email bounces, the receiving mail server often sends back a “delivery status notification” email. That email is usually multipart MIME, with pieces like:
message/delivery-status: structured delivery failure details, such as failed recipient, SMTP status code, reason.message/rfc822: a copy of the original email or original headers.message/global-headers: header-only metadata.These parts are not normal user attachments like invoice.pdf or image.png. They are technical sub-parts of the bounce email, and mail providers often expose them through the same attachments API even though they do not have a filename. Nylas returns filename: undefined.