How to Set SMTP relay on iis , useing 365 mail

Hi @Shai derhi

Did you follow the steps in this link to create a receive connector?
If yes, here is my configuration in IIS SMTP server:

1. In General, add local ip address of the IIS SMTP server and listen on port 25
   
2. In Access>Access control, select Anonymous access
   
   In Access>Relay, add the ip addresses of the devices which are allowed to relay via the IIS SMTP server
   
3. In Delivery>Outbound Security, select Anonymous access
   
4. In Delivery>Outbound connections, configure TCP port to 25
   
5. In Delivery>Advanced, configure Smart host to be the MX record of your domain
   
6. test sending an email and see if the recipient can receive it

This method doesn't require an existing mailbox in Office 365.
If you would like to use an existing mailbox, you may need to use SMTP AUTH.

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Please, note, that IIS SMTP is not supported to relay emails to Exchange OnPrem and/or Office 365. Support will refuse to resolve cases related to this. https://learn.microsoft.com/en-us/iis/application-frameworks/install-and-configure-php-on-iis/configure-smtp-e-mail-in-iis-7-and-above