postfix / thunderbird - connection refused
I currently have an Ubuntu server with Samba working as a domain controller. I also have postfix running on it which I'm having trouble connecting to through thunderbird from a client machine. the client can see the server but it comes up with the error message 'connection refused'. I think it may be an authentication thing so i disabled TLS and SASL (which i haven't set up) and did the same on thunderbird but get the same problem. Any ideas on this? Does postfix need TLS or SASL to work? Eventually I want Postfix to use the Ubuntu system user/passwords so that once a user logs on to the domain, they don't have to log in to their email as well.