We have SBS 2008 with Ex 2007 all patched to latest.
We have three FQDN's and they are setup in Exchange Management Console as accepted domains and we receive mail from them by manually adding the SMTP address to the user's mailbox in Recipient Configuration (perhaps problem 0.5?).
When "user A" receives an email using FQDN abc.com (the primary/reply address) they reply using that same address.
"User B" works remotely using FQDN def.com solely - I manually deleted and ABC.com SMTP addresses and added 2 @def.com SMTP addresses to the user's mailbox in Recipient Configuration.
When "user B" receives an email using FQDN def.com (the user's reply address) they reply using that same address.
"User C" works in office using UserC@abc.com as her primary email address. She also receives email from xyz.com (again manually added her an SMTP address). However when we want her to send an email from UserC@xyz.com - we open the 'From' box in Outlook 2010 and type the SMTP address into here (which seems to validate?) then when i send I get the following message back in the undeliverable email:
You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission.
Diagnostic information for administrators:
/O=FIRST ORGANIZATION/OU=EXCHANGE ADMINISTRATIVE GROUP (FYDIBOHF23SPDLT)/CN=RECIPIENTS/CN=me
We need User C to be able to send from both addresses as each address is relevant to a different 'brand' of our product.