SOGo 5.12.4: CalDAV/CardDAV XML parsing error at position 4733

Rink76

Hi,

I’m new to mailcow (running 2025-12) and still figuring things out. I’m trying to migrate from Exchange to mailcow, but I’m struggling with CardDAV/CalDAV connections from both macOS and Windows clients. IMAP works perfectly fine.

The Problem:
All DAV sync attempts fail with an XML parsing error at position 4733:

Outlook CalDAV Synchronizer (Windows): XML line 4733 error
eM Client (macOS): System.Xml.XmlException: Xml_MessageWithErrorPosition, Xml_UnexpectedTokenEx, 2, 4733
Apple Contacts/Calendar (macOS): Connection fails (likely same root cause)

What I’ve tried:

Base URL: https://mail.server.com/SOGo/dav/user@domain.com/
Full calendar URL: https://mail.server.com/SOGo/dav/user@domain.com/Calendar/personal/
Both attempts produce the same error

Additional context:

Fresh mailcow installation (2025-12) with SOGo 5.12.4
Empty calendars/contacts (no imported data yet)
Thunderbird partially works (contacts sync, but calendars don’t appear)
Server logs show successful PROPFIND requests (HTTP 207), so authentication works

Is this a known issue with SOGo 5.12.4, or am I missing something in the configuration? Happy to provide additional logs or config files if needed.

Thanks in advance!

SOLVED - XML Parse Errors Caused by Email Aliases with Ampersands

I found the root cause of my CalDAV/CardDAV synchronization issues!

The Problem:
Email aliases containing an ampersand character (e.g., user&name@domain.com) were causing SOGo to return invalid XML responses. The & wasn’t being properly escaped as & in the XML output, which caused all DAV clients with strict XML parsers to fail with errors like:

Xml_UnexpectedTokenEx at position 4733 (eM Client)
Xml_MessageWithErrorPosition (Outlook CalDAV Synchronizer)
XML parsing failures (Apple clients and others)

Why curl tests appeared to work:
Curl simply displays raw XML without parsing it, so manual PROPFIND tests didn’t reveal the issue. The problem only became visible when specifically requesting calendar-user-address-set properties, which exposed the un-escaped & characters in mailto: URIs.

The Solution:

Remove or rename all email aliases containing & characters in Mailcow
Use alternatives like -, ., or + instead (e.g., user-name@domain.com)
Restart SOGo: docker compose restart sogo-mailcow
Verify the XML is now valid with a PROPFIND test
Reconfigure your DAV clients

Result:
All clients now sync perfectly - eM Client, Outlook CalDAV Synchronizer, Apple Calendar/Contacts, and Thunderbird all work flawlessly.

Technical note:
While RFC 5322 technically allows & in the local part of email addresses, SOGo doesn’t properly escape it when generating XML responses, causing this issue. This appears to be a SOGo bug rather than a mailcow configuration problem.

Hope this helps anyone else encountering similar XML parsing errors with CalDAV/CardDAV!

ETNyx

Interesting, glad you worked it out. As part of SoGo, I would suggest reporting this issue.

Rink76 Use alternatives like -, ., or + instead (e.g., user-name@domain.com)

Just be aware that if you use +, it is considered as “tagged” email address by default. These addresses have a special meaning similar to Gmail, check your mailbox settings.