A mailbox is a child domain and B is parent. Both of them in one Exchange organization. How to access from B domain's mailbox to A domain's mailbox store in Exchange Mail server 2003.

There is nothing called child and parent mail box store. Under one AD forest , you can have only exchange organization. So where ever is the user (parent domain or child domain), the mail box always sits on the exchange org. So you can access any mail box , if you have the proper permission. Raj

On A's mailbox's security tab we have the following permissions: - Exchange Admin of B domain ( full access) - Exchange Domain Servers of B domain ( full access) But we are still not able to access A's mailbox from B's mailbox. What another permissions should be put on A's mailbox ?

Follow these steps on the server : In Active Directory Users and Computers, right-click the organization domain name, point to View, and then click Advanced Features. Click the Users container or the organizational unit where the user is located. Right-click the user account, and then click Properties. Click Exchange Advanced, and then click Mailbox Rights. Click Add to add a user to the list of users that are allowed to access this mailbox. In the permissions list, for the Full Mailbox Access permission, select the Allow check box.And on the Outlook follow this: MS Outlook 2003: Login to account in Outlook > Tools > Email Accounts > Make sure that view or change existing email accounts option is selected > next > change > more settings > Advanced > add > give the email of the required additional mailbox > ok > finish. MS Outlook 2007: Login to account in Outlook > Tools > Accounts settings > Select your Microsoft profile > change > more settings > Advanced > add > give the email of the required additional mailbox > ok > finish. Raj

Agreed with Raj In addition also take a look @ below article to understand the same http://telnetport25.wordpress.com/2008/02/09/exchange-2003-assigning-permissions-to-additional-mailboxes/Vinod |CCNA|MCSE 2003 +Messaging|MCTS|ITIL V3|

Im trying to connect between 2 exchange server for mailbox transfer. One of them configured as parent domain(parent.local). The another one is configured as child domain (chil.parent.local). I created PAR administarative group from parent domain, and i configured to browse that PAR administrative group while instaliing exchange server on child domain. Tried to access to PAR child domain group from CHIL parent domain group. but it doesn't acess and gives me this error ( shown picture -http://i2.photobucket.com/albums/y32/erdenekhuu/exchange.jpg) How do i access to PAR child domain admin? I cannot access to parent domain's mailbox store from child domain's mailbox store( same error shown picture -http://i2.photobucket.com/albums/y32/erdenekhuu/exchange.jpg)