Function deltachat::decrypt::get_attachment_mime

fn get_attachment_mime<'a, 'b>(
    mail: &'a ParsedMail<'b>,
) -> Option<&'a ParsedMail<'b>>

Returns a reference to the encrypted payload of a message turned into attachment.

Google Workspace has an option “Append footer” which appends standard footer defined by administrator to all outgoing messages. However, there is no plain text part in encrypted messages sent by Delta Chat, so Google Workspace turns the message into multipart/mixed MIME, where the first part is an empty plaintext part with a footer and the second part is the original encrypted message.