I'm searching for a method to connect exchange mailboxes with external mailboxes. I checked the EAC (found Send and Receive Connectors but they don't seem to be the right answer) and on web (found 3rd party software, which is used for downloading mails via pop3 or imap).

Now I am wondering if there is any build-in functionality in Exchange Server 2016 Standard for the following: Add and configure several mailboxes to Exchange which are connected to an existing mailbox of an external provider. For internal communication it is not necessary to send the mail over the external provider but if the mail goes external it should be send over the external provider.

Is there a smart solution for my problem? Build-in would be nice.

closed as unclear what you're asking by joeqwerty, peterh, MadHatter, Ward, mdpc Aug 24 '17 at 22:50

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Receiving: Depending on your MS Exchange setup you could get emails from a 3rd party environment to your Exchange environment via the following:

  1. Sync them via IMAP (e.g. via IMAPSync) and build a cron task here
  2. Use a POP3 collector as you already mentioned
  3. Forward the emails from the 3rd party account to your MS Exchange environment. You can configure a forward rule on the 3rd party system (if possible). But keep noted that (depending on the remote environment) you might get issues with S/MIME emails.

Keep noted that there is no "out of the box" solution to do that, as this approach above isn´t a common setup from MS Exchange. Therefore such solutions above will not be used in default setup and provided only a very bad workaround to build something which couldn´t be done the correct way.

Sending: Sending emails is a little bit tricky and depends on your environment:

You could configure the 3rd party server as relay and point your MS Exchange server to that relay. Then every MS Exchange email (external) is send over that relay. This could be done as a smart host configuration:

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Keep noted here that internal MS Exchange emails aren´t send via that relay as its a pure internal communication.

If you wish to setup a MS Exchange 2016 test environment and do not have a fixed public IP which would require that you wish to setup a construct above, you could build such a test environment with a dynamic IP as explained here. However keep noted this is for a test environment only!

  • Thank you very much for your answer! With the Send Connector I can't configure one-to-one connections, right? – hagenstrahl Aug 21 '17 at 13:24
  • What means one-to-one for you? That you send emails for joe.musterman@companyABC.tld via host exchange01.companyABC.tld and for joe.musterman@companyZZZ.tld via host exchange01.companyZZZ.tld? – BastianW Aug 21 '17 at 13:44
  • Yes. When I'm right the Send Connector is for a source server and not for a mailbox. So the credentials are used for each external mail like this: exchange01@domain.com and exchange02@domain.com will send via host with user01@company.com credentials. Or do I miss something? – hagenstrahl Aug 21 '17 at 13:59
  • hm, I think you miss some some knowledge here. The best way would be to start to check what a "relay host" is, that should answer your question in more details then I could do here. If you expect that you can add multiple entries here (e.g. every user got one entry) then this will not work. You need a relay host which will be used to send out all emails from the domain in charge here. – BastianW Aug 21 '17 at 14:23

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