[imp] Adding Exchange Account to MacBook

[john smith]

Hi,
I'm trying to add my Horde account to a MacBook.  I enter the username,
password and then it displays two fields with 'internal URL' and 'external
URL' with the message 'unable to verify the account username and password'.

The Horde is working fine - I have autodiscover pointing to the
/usr/share/horde/rpc.php but I don't know which URL to put into these two
fields.

Anyone help?.