Hai, Here I installed Exchange 5.5 in NT machine. Its is working fine. We are using Mailbox, Public Folders, calendar and OWA options by the Exchange server . Using Exchange we were enabled these services which I mentioned above. To sending and receiving e-mails through the third party software namely FTGate which is running under different NT machine. In such a case we were not able to send mail directly from the Mailbox. For the trial purposes we created only 30 mailboxes, those people were member of Exchange as well as in FTGate also. Other users they can send and receive e-mails through FTGate which are not member of the Exchange server. In this situation we can ?t add the third party tool in the Exchange server. Because all our mails will be downloaded into Exchange server, Exchange users can receive their mails. But not FTGate users. So that undelivered mails are stored in the Exchange server. Is there any solution for it. Fondly Lakshmanan K.