# Using EmailMessage with an attached email file crashes due to non-ASCII

**URL:** <https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981>\
**Category:** Mystery Errors\
**Created:** [January 15, 2025, 10:06pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981 "2025-01-15T22:06:06Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![stumpylog](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/stumpylog/32/16188_2.png) [@stumpylog](https://forum.djangoproject.com/u/stumpylog)\
**Post date:** [January 15, 2025, 10:06pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/1 "2025-01-15T22:06:06Z")

</div>

Given a basic email setup like below, when I try to send the message, I get the following traceback:

```auto
Traceback (most recent call last):
  File "/usr/src/paperless/src/documents/signals/handlers.py", line 989, in email_action
    n_messages = email.send()
                 ^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/core/mail/message.py", line 301, in send
    return self.get_connection(fail_silently).send_messages([self])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/core/mail/backends/smtp.py", line 136, in send_messages
    sent = self._send(message)
           ^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/core/mail/backends/smtp.py", line 156, in _send
    from_email, recipients, message.as_bytes(linesep="\r\n")
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/django/core/mail/message.py", line 148, in as_bytes
    g.flatten(self, unixfrom=unixfrom, linesep=linesep)
  File "/usr/local/lib/python3.12/email/generator.py", line 117, in flatten
    self._write(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 182, in _write
    self._dispatch(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 219, in _dispatch
    meth(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 286, in _handle_multipart
    g.flatten(part, unixfrom=False, linesep=self._NL)
  File "/usr/local/lib/python3.12/email/generator.py", line 117, in flatten
    self._write(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 182, in _write
    self._dispatch(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 219, in _dispatch
    meth(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 372, in _handle_message
    g.flatten(msg.get_payload(0), unixfrom=False, linesep=self._NL)
  File "/usr/local/lib/python3.12/email/generator.py", line 117, in flatten
    self._write(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 182, in _write
    self._dispatch(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 219, in _dispatch
    meth(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 446, in _handle_text
    super(BytesGenerator,self)._handle_text(msg)
  File "/usr/local/lib/python3.12/email/generator.py", line 263, in _handle_text
    self._write_lines(payload)
  File "/usr/local/lib/python3.12/email/generator.py", line 156, in _write_lines
    self.write(line)
  File "/usr/local/lib/python3.12/email/generator.py", line 420, in write
    self._fp.write(s.encode('ascii', 'surrogateescape'))

                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 UnicodeEncodeError: 'ascii' codec can't encode characters in position 10-15: ordinal not in range(128)

```

```python
email = EmailMessage(
    subject=subject,
    body=body,
    to=action.email.to.split(","),
)
email.attach_file(original_file)
n_messages = email.send()

```

The attached file is itself an eml file, which contains UTF8 content in the body. As far as I can figure, the `s.encode('ascii', 'surrogateescape')` is hardcoded. Has anyone worked around this? It seems like sending UTF8 content should be pretty easy.

---

<div class="post-metadata">

**Author:** ![BrunoMiglioretto](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/brunomiglioretto/32/26328_2.png) [@BrunoMiglioretto](https://forum.djangoproject.com/u/BrunoMiglioretto)\
**Post date:** [January 15, 2025, 11:53pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/2 "2025-01-15T23:53:25Z")

</div>

Hi, I sugest you try

`email.attach("file.eml", original_file, "message/rfc822")`

insted of

`email.attach_file(original_file)`

With `attach` method we can pass the MIME Type of the file.

---

<div class="post-metadata">

**Author:** ![stumpylog](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/stumpylog/32/16188_2.png) [@stumpylog](https://forum.djangoproject.com/u/stumpylog)\
**Post date:** [January 16, 2025, 12:15am UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/3 "2025-01-16T00:15:41Z")

</div>

Interesting idea, I had tried attach\_file, which can optionally take the MIME type, and providing that didn’t change anything.

So `email.attach_file(original_file, "message/rfc822")` didn’t work, nor did `email.attach(original_file.name, original_file.read_bytes(), "message/rfc822")`

---

<div class="post-metadata">

**Author:** ![anefta](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/anefta/32/10649_2.png) [@anefta](https://forum.djangoproject.com/u/anefta)\
**Post date:** [January 17, 2025, 11:55am UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/4 "2025-01-17T11:55:22Z")

</div>

Try to set the content type and charset explicitly:

```auto
email = EmailMessage(
    subject=subject,
    body=body,
    to=action.email.to.split(","),
)
email.content_subtype = 'plain'
email.encoding = 'utf-8'
email.attach_file(original_file)
n_messages = email.send()

```

---

<div class="post-metadata">

**Author:** ![medmunds](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/medmunds/32/22140_2.png) [@medmunds](https://forum.djangoproject.com/u/medmunds)\
**Post date:** [January 20, 2025, 11:01pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/5 "2025-01-20T23:01:58Z")

</div>

It looks like you’ve found a bug in Django’s EmailMessage: trying to add a message/rfc822 attachment that uses _Content-Transfer-Encoding: 8bit_ results in the error you’re seeing when the message is serialized.

Would you like to open a bug report at [https://code.djangoproject.com/](https://code.djangoproject.com/)?

A workaround is to parse the attached message into a Python Message object before attaching it:

```python
from email import message_from_bytes

email = EmailMessage(...)
email.attach(
    "file.eml",
    message_from_bytes(original_file_content),
    "message/rfc822",
)

```

(This prevents Django from calling Python’s `message_from_string(force_str(content))`, which seems to be the actual source of the problem.)

---

<div class="post-metadata">

**Author:** ![shamoon](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/shamoon/32/26404_2.png) [@shamoon](https://forum.djangoproject.com/u/shamoon)\
**Post date:** [January 21, 2025, 6:40pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/6 "2025-01-21T18:40:37Z")

</div>

Thanks for the suggestion, that does indeed work and is much simpler than the workaround we were using (MIMEBase stuff).

---

<div class="post-metadata">

**Author:** ![medmunds](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/medmunds/32/22140_2.png) [@medmunds](https://forum.djangoproject.com/u/medmunds)\
**Post date:** [January 21, 2025, 9:06pm UTC](https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981/7 "2025-01-21T21:06:33Z")

</div>

Thanks for bug report [#36119 (Attaching email file to email fails if the attachment is using 8bit Content-Transfer-Encoding) – Django](https://code.djangoproject.com/ticket/36119).

Just to follow up on some of the other suggestions from the thread:

- Including mimetype `"message/rfc822"` doesn’t really change anything when you’re attaching `file.eml`. Django tries to guess attachment type from the filename using Python’s [mimetypes.guess\_type()](https://docs.python.org/3/library/mimetypes.html#mimetypes.guess_type). And that function maps the `.eml` filename extension to “message/rfc822”. (But it never hurts to include the mimetype if you know it, particularly if the filename’s extension could be wrong.)
- The _undocumented_ EmailMessage.encoding property is almost never useful (unless you’re targeting really ancient email clients that don’t support Unicode), and setting it doesn’t help in this case. EmailMessage.encoding defaults to your [DEFAULT\_CHARSET](https://docs.djangoproject.com/en/5.1/ref/settings/#default-charset) setting, which itself defaults to utf-8.