• The legacyExchangeDN value is set when a mailbox is created and includes the name of the Exchange administrative group where the mailbox belongs.
Example LegacyExchangeDN: /o=Organisation/ou=Administrative Group/cn= Recipients/cn=Username
• X500 address stores the LegacyExchangeDN attribute in Active Directory.
• The legacyexchangeDN is used by exchange to send internal emails
Scenarios that requires the addition of x500 Addresses
• Converting a distrubtion list into a shared mailbox (email aliases are the same, however it would need the x500 to associate to the new sharedmailbox alias)
• Senders are receiving an NDR while responding to old emails of a returned e-mail (previous cached x500 stored no longer exist and will need the association)
How to gather the LegacyExchangeDN of a mailbox
1. From Exchange Management Shell
2. Run a Get-Mailbox -Identity [user] | ft LegacyExchangeDN
Get-Mailbox -Identity [user] | ft LegacyExchangeDN
Adding the X500 Address
1. From the Exchange Management Console (EMC)
2. Pull the reciepent from Receipent Configuartoin > Mailbox
3. Select Custom Address.. in the drop down next to Add… under E-mail Address Properties of the Recipent
4. E-mail Type is X500, E-mail Address is the [LegacyExchangeDN]. Should look like this: /O=EXCH/OU=EXCHANGE ADMINISTRATIVE GROUP (BLAH)/CN=RECIPIENTS/CN=EPIC@epiclau.com