Exchange and SMTP on the same network Local Mail failing

How are you forwarding traffic from one mail server to the next?  Basically, if the user doesn't exist on the exchange server, it needs to know to forward that message off to the other local server using a custom send connector. The reverse would be true for the SMTP server you've referenced.

It is just using DNS. The SBS server is handling the DNS.

Side Note: But that bring up a interesting point. I just look at the internal DNS for the SMTP server does not have an MX record. I added it. But I do not think that is affecting what is happening here. We are having an issue send from the SMTP to the SBS not the other way around.

DNS is important, yes. But this is a message routing issue.  First, the mail server needs to be authoritative to the domain it is receiving mail on, and if that mail server does not have a mailbox that corresponds to the user, then it needs to be forwarded to another mailbox server that may or may not have that mailbox.  This is done using a  sending rule on exchange, and some similar method must also be used for the unnamed SMTP server.

Suppose I have a MailServer1 with a mailbox for bob@xyzco.com, and MailServer2 has a mailbox for alice@xyzco.com.  If I send a message to MailServer1 with both Bob@xyzco.com & Alice@xyzco.com - I will get a bounce message for Alice.  If I send the message to MailServer2, I will get a bounce message for Bob. That is until I configure a forwarding rule on both servers that states that: While this server holds the mailbox for users in xyzco.com, it is not the ONLY mail server that exists for that domain.  If you receive a message for xyzco.com domain that you do not have a mailbox for, please forward that message to MailServerN for further processing.

Aaaaa I think I forgot one small piece of the pie. The two mail servers are completely different domains. One is xyzco.com and the other is abcde.com

X400 is the key, you need to type in the email address without hitting the ctrl-k

most likely, the X400/X500 address from Exchange is used when write the email in SMTP and of course, the SMTp server will not understand X400 and X500 address at all.

One thing, you might want to put in is to forwarding rules...

Even if we type in the whole SMTP email address it still does it.
I think Outlook thinks it knows better what needs to be done and it using the Exchange address even when we do not want it.

How would I do this?
One thing, you might want to put in is to forwarding rules

what is your SMTP server?
normal IIS or something else?

Post the bounce message please. Attempting to debug mail transport problems without a bounce message is really not going to help.

Outlook resolves addresses well enough in an Exchange system except where mailboxes have been moved between systems. In this case X500 addresses may be used to allow replies and cached address information to work. Beyond that X500 addresses are not necessary.

If it does it when you send a brand new mail, but Outlook is auto-completing for you, close outlook and rename the cache file (.NK2, hides somewhere in the users profile under AppData, I forget precisely where). Alternatively, for a case-by-case basis select addresses from the address book, do not let Outlook help suggest names.

Chris

If it really is showing an X400 address in the bounce message and you wish to permanently fix that (without users having to replace recipient addresses) the only real solution is to create an X500 address for each user. This is exceptionally difficult to do if you don't know the old legacyExchangeDN value (pre-migration). You'd have to pick the X400 address out of the bounce message and create an X500 address based on that on the recipients account.

Chris

It is outlook cached mode that is screwing you up then.  Delete your nickname files and it should take care of it.

Nickname files?

Aaa yes OK I can renew that file and see if it helps.