Good day, As recommended I set IIS to deny requests made without the Host header set. Unfortunately it does cause pop3 stop working. Could give any advice on this issue? Brgds Liu Wei

Hi @ wei liu , Welcome to the Microsoft Q&A platform! Based on your description, the configuration in IIS that denies requests without a Host header is interfering with your POP3 service. This happens because some services, such as POP3, may not include a Host header in their requests, causing them to be blocked by IIS. There are several steps you can take to resolve this issue: You can configure IIS to allow requests from the POP3 service by creating exceptions. This can be done by modifying the request filtering settings to exclude certain IP addresses or request types. Modify the request filtering settings: Open IIS Manager. Select the server or site for which you want to configure settings. In Features View, double-click Request Filtering. In the Actions pane, click Edit Feature Settings. Adjust the settings to allow requests without a Host header for specific services or IP addresses. If you have the URL Rewrite module installed, you can create a rule to bypass the Host header check for POP3 requests. Open IIS Manager. Select the server or site. In Features View, double-click URL Rewrite. Add a new rule to allow requests without a host header for the POP3 service. Make sure your POP3 service is correctly configured to work with IIS. Sometimes adjusting the service settings can solve the problem. Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer. Best, Jake Zhang

configure the IIS server to deny requests made without the Host header set.

Accepted answer

Jake Zhang-MSFT 6,375 Reputation points Microsoft Vendor

2024-10-02T08:02:42.9866667+00:00
Hi @wei liu,

Welcome to the Microsoft Q&A platform!

Based on your description, the configuration in IIS that denies requests without a Host header is interfering with your POP3 service. This happens because some services, such as POP3, may not include a Host header in their requests, causing them to be blocked by IIS.

There are several steps you can take to resolve this issue:

You can configure IIS to allow requests from the POP3 service by creating exceptions. This can be done by modifying the request filtering settings to exclude certain IP addresses or request types.

Modify the request filtering settings:

Open IIS Manager.

Select the server or site for which you want to configure settings.

In Features View, double-click Request Filtering.

In the Actions pane, click Edit Feature Settings.

Adjust the settings to allow requests without a Host header for specific services or IP addresses.

If you have the URL Rewrite module installed, you can create a rule to bypass the Host header check for POP3 requests.

Open IIS Manager.

Select the server or site.

In Features View, double-click URL Rewrite.

Add a new rule to allow requests without a host header for the POP3 service.

Make sure your POP3 service is correctly configured to work with IIS. Sometimes adjusting the service settings can solve the problem.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang
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Jake Zhang-MSFT 6,375 Reputation points Microsoft Vendor

2024-10-04T08:22:39.2766667+00:00

Hi @wei liu,

Please kindly consider this comment as a warm follow up, I want to know if your problem has been solved. If you still have any other questions, please feel free to comment here and I'm glad to provide further support.If the above info is helpful to this question, you can click "Accept Answer". Have a nice day!

Best,

Jake Zhang

Jake Zhang-MSFT 6,375 Reputation points Microsoft Vendor

2024-10-11T08:15:36.8933333+00:00

Hi @wei liu,

Is there any update on this thread? If the issue has been resolved, please mark the helpful replies as answers, this will make answer searching in the forum easier and be beneficial to other community members as well. Thanks for your understanding.

Best,

Jake Zhang

wei liu 41 Reputation points

2024-10-18T06:59:47.9733333+00:00

Good day, Jake,

High appreciated your help.

Try follow the guide. I could not find the feature setup in Request Filterring.

and URL Rewrite. I have no idea in Request Filterring and URL Rewrite setup provided.

See attached screenshot.

Brgds

Liu Wei

Jake Zhang-MSFT 6,375 Reputation points Microsoft Vendor

2024-10-22T09:57:35.5+00:00

Hi @wei liu,

I'm glad to help you further. You can't seem to find the Request Filtering feature and set up URL Rewrite rules in IIS. Let's look at the steps in more detail:

Request Filtering

Open IIS Manager.

Select your site from the Connections pane.

In Features view, you should see an icon for Request Filtering. If it's not there, it's probably not installed. You can add it through Server Manager:

Go to Manage > Add Roles and Features.

Navigate to the Roles section in the wizard.

Under Web Server (IIS) > Web Server > Security, make sure Request Filtering is checked. - Complete the wizard and install the feature if it's not already installed.

URL Rewriting

Open IIS Manager.

Select your site from the Connections pane.

In Features view, look for URL Rewrite. If you don't see it, you'll need to install it:

Download the URL Rewrite module from the IIS website.

Run the installer and follow the prompts.

Restart IIS Manager and you should see the URL Rewrite options.

Once you have these you can move on to setting up the rules to allow POP3 requests through IIS.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang
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