Still UnicodeEncodeError: 'ascii' codec can't encode characters in position 300-301

[magoralczyk]

I have read here in the closed issues, that this problem has been fixed last year, maybe it is another one. I do not know, how to get to the problematic mail. I am assuming certain messages (because I see the files in the dest folder, which go up by date, until it breaks down), but when I move a lot of files in this timeframe into a nonsynced folder, the output does not change. I do not know how to analyze the problem.

Here is the complete output when syncing:

$ offlineimap -a martin
OfflineIMAP 8.0.1
Licensed under the GNU GPL v2 or any later version (with an OpenSSL exception)
imaplib2 v3.06, Python v3.12.12, OpenSSL 3.0.18 30 Sep 2025
Account sync martin:
*** Processing account martin
Establishing connection to mailsrv1:143 (martinremote)
Folder ablage [acc: martin]:
Creating new Local Status db for martinlocal:ablage
Folder Archive [acc: martin]:
Creating new Local Status db for martinlocal:Archive
Folder ablage [acc: martin]:
Syncing ablage: IMAP -> Maildir
Folder Archive [acc: martin]:
Syncing Archive: IMAP -> Maildir
Folder Drafts [acc: martin]:
Creating new Local Status db for martinlocal:Drafts
Syncing Drafts: IMAP -> Maildir
Folder INBOX [acc: martin]:
Creating new Local Status db for martinlocal:INBOX
Syncing INBOX: IMAP -> Maildir
Folder Junk [acc: martin]:
Creating new Local Status db for martinlocal:Junk
Syncing Junk: IMAP -> Maildir
Folder memos [acc: martin]:
Creating new Local Status db for martinlocal:memos
Syncing memos: IMAP -> Maildir
Folder Sent [acc: martin]:
Creating new Local Status db for martinlocal:Sent
Syncing Sent: IMAP -> Maildir
Folder Trash [acc: martin]:
Creating new Local Status db for martinlocal:Trash
Syncing Trash: IMAP -> Maildir
Folder ablage [acc: martin]:
Copy message UID 11422 (11404/16614) martinremote:ablage -> martinlocal:ablage
Copy message UID 11423 (11405/16614) martinremote:ablage -> martinlocal:ablage
Copy message UID 11425 (11406/16614) martinremote:ablage -> martinlocal:ablage
Copy message from martinremote:ablage:
ERROR: Copying message 11422 [acc: martin]
'ascii' codec can't encode characters in position 300-301: ordinal not in range(128)
Thread 'Copy message from martinremote:ablage' terminated with exception:
Traceback (most recent call last):
File "/usr/local/lib/python3.12/site-packages/offlineimap/threadutil.py", line 146, in run
Thread.run(self)
File "/usr/lib/python3.12/threading.py", line 1012, in run
self._target(*self._args, **self._kwargs)
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Base.py", line 827, in copymessageto
new_uid = dstfolder.savemessage(uid, message, flags, rtime)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Maildir.py", line 408, in savemessage
tmpname = self.save_to_tmp_file(messagename, msg)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Maildir.py", line 359, in save_to_tmp_file
fd.write(msg.as_bytes(policy=output_policy))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/email/message.py", line 208, in as_bytes
g.flatten(self, unixfrom=unixfrom)
File "/usr/lib/python3.12/email/generator.py", line 117, in flatten
self._write(msg)
File "/usr/lib/python3.12/email/generator.py", line 182, in _write
self._dispatch(msg)
File "/usr/lib/python3.12/email/generator.py", line 219, in _dispatch
meth(msg)
File "/usr/lib/python3.12/email/generator.py", line 286, in _handle_multipart
g.flatten(part, unixfrom=False, linesep=self._NL)
File "/usr/lib/python3.12/email/generator.py", line 117, in flatten
self._write(msg)
File "/usr/lib/python3.12/email/generator.py", line 182, in _write
self._dispatch(msg)
File "/usr/lib/python3.12/email/generator.py", line 219, in _dispatch
meth(msg)
File "/usr/lib/python3.12/email/generator.py", line 278, in _handle_multipart
self.write(subparts)
File "/usr/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 300-301: ordinal not in range(128)

Last 2 debug messages logged for Copy message from martinremote:ablage prior to exception:
thread: Register new thread 'Copy message from martinremote:ablage' (account 'martin')
maildir: Write mail 'ablage:11422' with flags {'S'}
ERROR: Exceptions occurred during the run!
ERROR: Copying message 11422 [acc: martin]
UnicodeEncodeError: 'ascii' codec can't encode characters in position 300-301: ordinal not in range(128)

Folder ablage [acc: martin]:
Copy message UID 11426 (11407/16614) martinremote:ablage -> martinlocal:ablage

Traceback:
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Base.py", line 827, in copymessageto
new_uid = dstfolder.savemessage(uid, message, flags, rtime)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Maildir.py", line 408, in savemessage
tmpname = self.save_to_tmp_file(messagename, msg)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/offlineimap/folder/Maildir.py", line 359, in save_to_tmp_file
fd.write(msg.as_bytes(policy=output_policy))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/lib/python3.12/email/message.py", line 208, in as_bytes
g.flatten(self, unixfrom=unixfrom)
File "/usr/lib/python3.12/email/generator.py", line 117, in flatten
self._write(msg)
File "/usr/lib/python3.12/email/generator.py", line 182, in _write
self._dispatch(msg)
File "/usr/lib/python3.12/email/generator.py", line 219, in _dispatch
meth(msg)
File "/usr/lib/python3.12/email/generator.py", line 286, in _handle_multipart
g.flatten(part, unixfrom=False, linesep=self._NL)
File "/usr/lib/python3.12/email/generator.py", line 117, in flatten
self._write(msg)
File "/usr/lib/python3.12/email/generator.py", line 182, in _write
self._dispatch(msg)
File "/usr/lib/python3.12/email/generator.py", line 219, in _dispatch
meth(msg)
File "/usr/lib/python3.12/email/generator.py", line 278, in _handle_multipart
self.write(subparts)
File "/usr/lib/python3.12/email/generator.py", line 420, in write
self._fp.write(s.encode('ascii', 'surrogateescape'))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^