IIS SMTP Relay Services

I would like to talk about the IIS SMTP Relay Service. We have a lot of customer which uses CRM, SAP, and Marketing Application and so on to send out bulk emails. Sometimes monthly statements. What happens when you your mail provider has a limit which most providers do? Firstly, this is put in to protect your domain and IP from getting blacklisted. Then secondly, how do you get around the limitations when the application you are sending from cannot manage the amount of connections it establishes with the Relay platform? I know with past experience a lot of web sites have a scripted SMTP Send in them which there is no advance configuration to manage the connection. Therefore, the remedy is an IIS SMTP Relay Service.

How to set up the IIS SMTP Relay Services?

  1. Ensure IIS Server Role has been installed on the server. If not, please install the Role.
  2. Then install the “SMTP Server” Role.
  3. Once you have completed installing the Roles, it is time to configure the SMTP Service.


  1. Launch the IIS Manager.
  2. You will find an SMTP Virtual server, right-click
  3. On the “Access” tab, select “Relay Restriction”
  4. Ensure for security purposes that you select “Only the list below” and add the IP addresses of the systems which you would like to allow mail relay.



The three most important tabs are the:

  1. Delivery tab – Outbound security

  1. Advanced Delivery – Smarthost configuration
  2. Outbound Connections – Setting connection limits



By configuring the above, gives you control of limitation and securely not allowing any unrecognized systems sending on behalf of your domains. Most people think, “another step for just making an email sending facility work! “, however, from our security side, it is just more reinforcement and help you control your system to meet our halfway.




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