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https://github.com/OfflineIMAP/offlineimap3.git
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Rodolfo García Peñas (kix)
0185b11255
When fetching emails with defects or malformed bytes (e.g., spam or broken MIME boundaries), the Python 3 `email.parser` handles un-decodable bytes by safely substituting them with the Unicode Replacement Character `\ufffd` (using the `errors='replace'` handler by default). However, a problem arises during the `_fetch_from_imap` sync process when OfflineIMAP3 tests if the message can be serialized back to bytes via `as_bytes()`. If the malformed text part was originally declared as `us-ascii` (or left unspecified, defaulting to ASCII), Python attempts to encode the `\ufffd` string back to bytes using the ASCII codec. Since `\ufffd` is out of the ASCII range, this triggers a `UnicodeEncodeError`, causing OfflineIMAP3 to raise an `OfflineImapError` and entirely skip syncing the message. This commit fixes the issue by catching the `UnicodeEncodeError` when `as_bytes()` fails. It then walks through the message parts, identifies the text payloads that cannot be encoded with their current charset, and dynamically forces their charset to `utf-8`. This allows Python to safely encode the `\ufffd` character (automatically applying base64/quoted-printable transfer encoding if needed), successfully serializing the message so it can be synced without crashing. Closes #240 Closes #229 Closes #224 Closes #160