When trying to access Horde it shows an error below when you click on Log In. Even if you use the correct login details it does not allows you to enter.
Message Login failed because your username or password was entered incorrectly.
This is because due to incorrect permissions on the files & directories on etc & mail directory under the account. Login to your server via SSH & execute commands below.
Once the updates are completed, try accessing the Horde. It should allow you to enter.