I want to use Thunderbird with Exchange 2007. Before I used Outlook and everything worked fine. Now I set up the following settings in Thunderbird:

Server Address:
Port: 143
Authentication: Password, normal

Server Address:
Port: 587
Authentication: No

The user can send and receive emails from inside the organization. Now the user should also send and receive emails outside the organization. If the user tries it he gets Unable to relay and no message is sent. This is an authentication problem.

How should the Exchange 2007 server be configured?

I tried other settings for the outbox within Thunderbird but they didn't worked. In the Exchange management consonsole I go to server configuration, client access, POP3 and IMAP4, click on the properties of POP3 and I have the following settings:

TLS: Port 110
SSL: Port 995

Secure login and the name of the X.509 certificate

Under server configuration, Hub-Transport, properties of the default connector, tab authentication TLS, basic authentication and integrated Windows authentication is checked. Under authorisation group anonym user, exchange user, exchange server and legacy exchange server is checked.

  • Thunderbird + Microsoft Exchange is a pretty poor experience in my opinion... However, you should be able to get this to work. Why are you using IP addresses instead of hostnames?
    – ewwhite
    Feb 7, 2013 at 11:12
  • @ewwhite: Yeah I know ... I looked for configurations which I found in the net and there somebody used the IP address. But I didn't get it managed to work with mail.yourdomain.com in the server address settings for IMAP and SMTP ...
    – testing
    Feb 7, 2013 at 11:17

1 Answer 1


SMTP should be configured to require authentication if you are publicly exposing the ports. Most default configs only allow relaying as authenticated users.

By "outside the org" are you leaving the network? Are you using VPN to connect to mail.yourdomain.com is probably resolving to a public IP address, which would be unreachable while you are inside the network, and would only work outside the firewall if you had your IMAP/SMTP ports open to the Exchange server.

I think that if you were to configure your client to authenticate against both IMAP and SMTP, you would at minimum be working inside your firewall, pointed at

To get it working outside the firewall with a local address, you would need to VPN.

If you don't want to VPN, and want to use mail.yourdomain.com, you could setup the yourdomain.com zone on an internal DNS server (assigned to clients with DHCP) and have it resolve mail.yourdomain.com to, and when you are outside the firewall, public DNS would resolve it to the correct public IP.

  • With "outside the org" I mean that the user can send to a gmail account not only to a mail account in the domain. So I'm in the network. There is an authentication for the incoming mails but there is no authentication for sending the emails. I tried to set up authentication in Thunderbird but it didn't worked. So how do I have to configure the authentication on the E2K7 server?
    – testing
    Feb 13, 2013 at 16:39

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