cannot parse part "multipart/mixed" with boundary

[bsc-computer]

Part of eml-file

`X-MS-Exchange-Organization-Processed-By-Gcc-Journaling: Journal Agent
Content-Type: multipart/mixed;
boundary="a5093c80-52fc-4ad9-bca7-3906fe47922d"

--a5093c80-52fc-4ad9-bca7-3906fe47922d
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable`

code

email, err := letters.ParseEmail(r) if err != nil { log.Fatal(err) }

output

letters.parsers.parsePart: cannot parse Content-Disposition: letters.parsers.parseContentDisposition: unknown Content-Disposition "attachfile"

Normaly letters works fine.
It seems a special structure of this emails
I have some eml-files to produce the error. (Only via private mail)

workaround

(with standard go libraries isit possible to extract attachments without errors)

`package main

import (
"encoding/base64"
"fmt"
"io"
"mime"
"mime/multipart"
"net/mail"
"os"
"strings"
)

func main() {

emlFile, err := os.Open(`test.eml`)
if err != nil {
	panic(err)
}
defer emlFile.Close()


msg, err := mail.ReadMessage(emlFile)
if err != nil {
	panic(err)
}

// Get MIME-Typ
mediaType, params, err := mime.ParseMediaType(msg.Header.Get("Content-Type"))
if err != nil {
	panic(err)
}

//  multipart-message?
if strings.HasPrefix(mediaType, "multipart/") {
	mr := multipart.NewReader(msg.Body, params["boundary"])
	for {
		p, err := mr.NextPart()
		if err == io.EOF {
			break
		}
		if err != nil {
			panic(err)
		}

		if cd := p.Header.Get("Content-Disposition"); strings.Contains(cd, "attachFile") {
			filename := p.FileName()

			//  Content-Transfer-Encoding-Header
			var reader io.Reader
			switch p.Header.Get("Content-Transfer-Encoding") {
			case "base64":
				reader = base64.NewDecoder(base64.StdEncoding, p)
			default:
				reader = p
			}

			data, err := io.ReadAll(reader)
			if err != nil {
				panic(err)
			}

			// save attachment to file
			err = os.WriteFile(filename, data, 0644)
			if err != nil {
				panic(err)
			}
			fmt.Printf("attachment %s saved\n", filename)
		}
	}
}

}
`

[manuraj17]

@bsc-computer Could you share the Content-Disposition header or a bit more elaborate sample eml file with which we can reproduce this?