Active Directory Same Account name

I am two Active Directory Domains. Now here both the domains share the same exchange system. And the users also share the same exchange mailboxes. The issue here is that however when I configure the directory sync on the domain the user information is uploaded properly. But on the same hand when I sync the other one it deletes the user information form the domain. Does this means that the users are sharing a common email address. Quiet confused in this process. Any suggestion really appreciated.

Let see that the solution will help you or not. Go to Admin > Directory Sync > Advance Filtering > Organization Hierarchy Mapping > Set Up Org Mapping. Then here in the console you will have to collect all the org name of each and every organization including all the users. Then on the directory server set a custom attribute which has this information. Now do this carefully f you will have to set attribute to separately synchronize each organization unit on the message security service. Then configure the Org mapping attribute. You will have to configure it to the name of the attribute which is going to used on the server.

The problem seems to be a complicated one. I hope this can sort you out. You will need ADSIEdit for this. By this you have to populate an unused OU attribute. Run the service and go to the OU. The select properties by right clicking on it . Search an unused attribute. Then click edit and give a value to the attribute. Then set the org mapping attribute to AD attirbute in the Postini Directory Sync configuration page.

See the settings in SAM Account Name attribute. The attribute is displayed as sAMAccountName. This attribute enables users to share a common user name. Size must be less than 20 characters. The attribute id is 1.2.840.113556.1.4.221. Just configure that and see weather you have done of not. Try to collect some more resources on it. The msdn site offers you an entire guide which will provide you information on the attribute.