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pavankumar-6152 avatar image
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pavankumar-6152 asked KyleXu-MSFT answered

Office 365 to on-prem mail flow

HI,
i have a requirement from my client that they want emails from o365 to on-prem to route via a DMZ rather having a direct connection. is there any solution that i can use it. ?

i am thinking of using a server with role/feature installing a SMTP and make inbound from o365 to on-prem pass thru this. is it possible? i have never tried it, does anybody tried it?

any ideas is appreciated.

Thanks
Pavan.

office-exchange-server-administrationoffice-exchange-online-itprooffice-exchange-server-mailflowoffice-exchange-hybrid-itpro
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KyleXu-MSFT avatar image
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KyleXu-MSFT answered

@pavankumar-6152

You can use ForcePoint SMTP gateway between Exchange on-premises and Internet, but you cannot add it between Exchange on-premises and Exchange online.

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Why not install an Edge in DMZ, then let mail flow sent to Edge server from Office 365, then sent to Exchange on-premises?
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AndyDavid avatar image
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AndyDavid answered AndyDavid commented

Are they hybrid mode? Be aware:
https://docs.microsoft.com/en-us/exchange/transport-routing


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Othrewise, you can use any SMTP gateway to do this, including the on-prem Exchange Edge role.
You could just use an IIS server with SMTP installed.


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Yes, they are hybird mode.

and they are using a ForcePoint SMTP gateway for external emails both inbound and outbound. but it is not working for o365 to external (gmail, outlook.com) via internal. the email is getting rejected at the gateway.

if i can use just the IIS server for SMTP then that would be great.?

Thanks
Pavan.

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Sure you can do. Its Just SMTP.

If its begin rejected, then something is not configured right on ForcePoint or Hybrid is not configured correctly for centralized mail flow

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