Oh.. one more thing the Tech at the Apple store is correct you do have to enable SMTP based authentication to send on the mail client ( That is the default setting with Exchange 2000 and 2003 ). But that would be required with all Mac and PC based clients that are non domain members and are not using Outlook in MAPI mode. Jose -------------------------------------------------------- -----Original Message----- From: Medeiros, Jose Sent: Friday, July 15, 2005 9:06 AM To: [ExchangeList] Subject: [exchangelist] RE: MAC vs Exchange 2000 SP 4 http://www.MSExchange.org/ This is just a guess but it sounds like your having an issue with reverse DNS lookups. I have used MAC OS 9-10.3 with an Exchange 2000 and 2003 server and have not had the issues that you are having. I am also assuming that your using POP or IMAP on the MAC clients. If your using MAPI in Entourage what version are you running? Jose -----Original Message----- From: Hermano JS. Queiroz [mailto:hjsqueiroz@xxxxxxxxxxxxxxxxxx] Sent: Friday, July 15, 2005 5:42 AM To: [ExchangeList] Subject: [exchangelist] MAC vs Exchange 2000 SP 4 http://www.MSExchange.org/ Hi Everyone, I'm dealing with a weird situation involving some Mac units using Entourage or even Mail 1.3.9 as client and I got different messages all the time. All three machines are behind the firewall as well as our Exchange server, so it is using the same range of private IP address 10.X.X.X . For some unknown reason when I telnet the Exchange Server using these MAC, I got timeout message, but using PC it is ok and also we do have other Eudora Client (PC) and it is working fine, only with MAC. The messages are: 1- The attempt to read data from the server "10.x.x.x." failed. Mail 1.3.9 V (619) 2- Finger Connection Refused 3- Connection Closed by Foreign Host 4- Error - This message could not be delivered and will remain in your outbox until it can be delivered + Ok Microsoft Exchange 2000 POP Server Version 6.0.6603.0 (<server name>) Ready! Any clue, thoughts, advises or whatever will be really appreciated! PS. All message related above I already tried to found some reasons, but Microsoft website and others known forums doesn't give me an specific clue. Someone from an Apple store was saying that the machine needs to be authenticated on the server, and I'm not sure if I need to have any appletalk plug-in or any service from exchange needs to be active, because was working before and suddenly start to quit one by one. Thanks again! Hermano