Hi there, We have a client that using thunderbird and he can recieve/send email fine (both internal and external users). problem starts when we install exchange 2010 (on different server) for testing and suddenly he gets the unable to relay error message if he tried to send email to external users (I don't remember the exact saying since it's in french, but it sounds like he didn't have permission to relay). sending email to internally is fine though. Some people recommend to check the DNS under exchange mgmt console to see which DNS registered with the server. when we check it on exchange 2007, it suddenly pops out quite a few error messages saying something about can't access table name xxx. and almost all tabs are not configurable. Our exchange 2007 still the main mail server while Exchange 2010 is just standing there. but it somehow manage to "integrate" with the current system (recognized other exchange servers, see mailboxes, etc). Any thought on this?Andrew P.

Hi, Ypu must either have the client authenticate when sending e-mails or allow anonymous relay on the receive connector. http://technet.microsoft.com/en-us/library/bb232021.aspx Don't allow relay on the receive connector where you receive internet mails and make sure that you use IP address limitations on this connector Leif

Hi Andrew Do other users who use outlook work well? We should narrow down the range of error. According to your saying, I find similar case about 550.5.7.1. Maybe it will be helpful to you. Maybe you can ask error id from your user. Exact ID can also narrow down the range of error. Then I also read the guide of Setup Mozilla Thunderbird to work with Microsoft Exchange Server Thunderbird use IMAP protocol. So you should check the port of 993 and SSL encryption port and IMAP4 works well. These kbs are reported by thunderbird users. Maybe they are helpful to you. Users do not receive new messages if they use IMAP4 clients to access mailboxes that were moved to another Exchange Server 2010 RU1 server. Certain third-party IMAP4 clients cannot connect to Exchange Server 2003 mailboxes through an Exchange Server 2010 CAS server All the resolutions are to update version of exchange 2010. Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

Apologies for the late reply. after several troubleshooting, we just found out that he's using the wrong server as outgoing smtp, which is not allowing external email relay. I tried to set up our current exchange server 2007 to act as the outgoing smtp server but also have some issues. this will be posted on a separate post. again, sorry for not researching the issue properly.Andrew P.