[horde] H6 Active Sync authentication error

[Andreas Mauser]

April 13, 2026 at 8:05 AM, horst.simon2 at icloud.com mailto:horst.simon2 at icloud.com  wrote:


> 
> Active Sync gives me authentication error, the username (horst at address.net) is the full email address, but when I check the logs it shows only the name from before the @. 
> Carddav and Caldav authenticating correct.
> Following are the log entries:
> 2026-04-13T15:34:43+10:00 DEBUG: HORDE [horde] Horde_Rpc::__construct complete [pid 3228 on line 48 of "/opt/local/www/apache2/horde/vendor/horde/rpc/lib/Horde/Rpc/ActiveSync.php"]
> 2026-04-13T15:34:43+10:00 DEBUG: HORDE Horde_Rpc_ActiveSync::getResponse() starting for OPTIONS [pid 3228 on line 197 of "/opt/local/www/apache2/horde/vendor/horde/horde/rpc.php"]
> 2026-04-13T15:34:47+10:00 NOTICE: HORDE Login failed from ActiveSync client for user horst. [pid 3228 on line 603 of "/opt/local/www/apache2/horde/vendor/horde/activesync/lib/Horde/ActiveSync.php"]
> 2026-04-13T15:34:47+10:00 NOTICE: HORDE Sending HTTP 401 Unauthorized header response. [pid 3228 on line 129 of "/opt/local/www/apache2/horde/vendor/horde/rpc/lib/Horde/Rpc/ActiveSync.php"]

It could be one of these:

Navigate to Administration > Configuration > Horde > ActiveSync.
Look for a setting typically labeled "Strip domain part from the username?" or "Username format".

Check your horde/config/conf.php. Horde might be configured to globally treat the username as a simple string.
Look for your authentication driver configuration:

PHP
$conf['auth']['params']['strip_domain'] = true;


Check your imp/config/backends.local.php.
If you have a configuration for your IMAP server, ensure the hordeauth parameter is handled correctly. If ActiveSync tries to authenticate against the mail server to "verify" the user, and the mail server expects horst at address.net but receives horst, it will fail.
Ensure your backend has:

PHP
'hordeauth' => 'full',


Best regards,
Andreas


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Mit freundlichen Grüßen,
Andreas Mauser
+49 160 551 1166
Frankfurt am Main

Andreas ist keine KI und kann Fehler machen, auch bei Informationen über Personen.