Affected Components: Mailbox / Message viewer (shell-ui), MIME rendering
Description: Emails containing inline images referenced via <img src="cid:..."> render broken in the message viewer. The cid: URI is never rewritten to a real,
fetchable URL, so the browser throws net::ERR_UNKNOWN_URL_SCHEME trying to load it directly. Regular attachments (PDF, image attachments, spreadsheets) work fine —
only body-embedded images are affected. This appears to be a known issue reported by other users since 2023, apparently still open in this version.
Server OS: Ubuntu 24.04 LTS
Carbonio Version: 26.6.2 (Community Edition)
Current Behavior: Inline image shows as broken/missing in the message body; browser console shows net::ERR_UNKNOWN_URL_SCHEME for a cid:... "URL".
Expected Behavior: The cid: reference should be resolved to the actual attachment part and rendered inline, as in Zimbra classic.
Steps to Reproduce:
1. Receive (or migrate via imapsync) an email whose HTML body embeds an image via Content-ID, e.g. <img src="cid:image001.png@...">.
2. Open the message in the Carbonio web UI.
3. The inline image fails to load; browser devtools console shows net::ERR_UNKNOWN_URL_SCHEME.
4. Confirmed on both migrated mail (imapsync from Zimbra) and newly SMTP-delivered mail — not limited to migrated content.
5. Note: behavior is inconsistent — some inline images from other senders/MUAs render correctly, suggesting it depends on how the originating client constructs the
Content-ID/multipart structure.
Link: N/A (happy to provide a reproducible sample .eml if useful)