Hybrid Exchange and third-party SMTP mail gateway

adam900331 361 Reputation points
2021-11-24T07:13:44.347+00:00

Hy!

I have an on-premise Exchange 2013 and a third-party mail gateway. I want to create a Hybrid Configuration whit this on-premise configuration. I want to use centralized mail flow. I have a plan, can you validate it?

  1. The MX record i pointing to the on-premise third-party mail gateway which handle the mail flow:from the internet to the on-premise and from the on-premise to the internet.
  2. I have a correct Virtual Directory configuration, all URL set to https://mail.domain.com/
  3. I have correct autodiscover configuration in DNS, which point to the on-premise Exchange with 443/TCP.
  4. I will install the public SSL certificate on the mail gateway for the secure mail transport between the on-premise and EXOmail flow.
  5. I found an article: https://www.codetwo.com/admins-blog/office-365-hybrid-configuration-wizard-step-by-step/
  6. What can I obtain the "Oragnization FQDN" step? In my interpretation it is the FQDN that the EXO use to send the emails into the on-premise Exchange? So I thin it is the MX record, which can handle the 25/TCP in mail gateway. Is it correct? The above URL say: "On this address, the Exchange server is listening on port 25 and 443 (EWS, OWA). FQDN’s format usually is like in this example: mail.domain.com." I think it is valid if I don't use third party mail gateway in on-premise environment, isn't it?
  7. How works the free/busy between EXO and on-premise Exchange? I think the EXO will use the autodiscover to get the correct URL for EWS: https://mail.domain.com/EWS/exchange.asmx Is it correct?
  8. I would like to send the EXO email through the on-premise third-party mail gateway, so in my interpretation I can reconfigure manually the on-premise O365 send connector to use the smart host. Is it correct?
  9. Can I configure anything else?

Thanks.

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
7,373 questions
Microsoft Exchange Hybrid Management
Microsoft Exchange Hybrid Management
Microsoft Exchange: Microsoft messaging and collaboration software.Hybrid Management: Organizing, handling, directing or controlling hybrid deployments.
1,905 questions
Accepted answer
  1. KyleXu-MSFT 26,211 Reputation points
    2021-11-25T02:38:23.513+00:00

    @adam900331

    "6": You need use to "mail.domain.com" and make sure this record point to your Exchange on-premises directly. You cannot put any service between Exchange on-premises and Exchange online.:
    152461-qa-kyle-10-28-16.png

    "7": HCW will configure free/busy for your directly. If you want to adjust it, you could manage it from this place below:
    152359-qa-kyle-10-31-45.png

    "8": Run HCW to create send/receiver connectors automatically which could make sure the mail flow between Exchange on-premises and Exchange online. After that, if you want to add third-party mail gateway, you could create send connector for it manually.

    "9": Personally, in a hybrid organization. I would suggest you use Exchange online as incoming server. Exchange online provide free EOP to protect the security of mail flow. If you want a more secure configuration, you can buy a standalone EOP.

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