HTTP ERROR 400 - Problem accessing /service/preauth

[adnese]

Hello,

one mailbox cannot be used; after trying to login with valid creds 'wrong username or password' message is shown. Logging to the mailbox from the admin interface brings:


HTTP ERROR 400

Problem accessing /service/preauth. Reason:

hmac failure

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Tried to change the user status without effect.

Thanks for any hint.

Regards,

Adrian