[exim] no response from Exim server (4.43)

Hi,

my Exim server seems to be sending/receiving mail for local users fine, but
I just noticed an error while in my Account configuration in Outlook 2003...

There's a button to test the account settings; all tests ok, except for the
'test e-mail' which returns the following error no matter what I've tried so
far:

'Send test e-mail message: The specified server was found, but there was no
response from the server. Please verify that the port and SSL information
is correct.'

So why would the server not respond? Following are some of my Exim config
settings:

#auth_advertise_hosts = ! 192.168.1.0/24
#auth_advertise_hosts = ${if eq{$tls_cipher}{}{}{*}}
auth_advertise_hosts = *
tls_advertise_hosts = *
tls_certificate = /etc/exim/certs
tls_privatekey = /etc/exim/privkey
#server_advertise_condition = ${if eq{}{$tls_cipher} {no} {yes} }

I'm using Courier for my POP3/IMAP servers, if that has anything to do with
it.

TIA for your help!
Robert