When running a file from a mapped drive you might get this error.

This is actually a Windows security message, intended to remind users not to open untrusted files downloaded from the Internet, but if you know that there is no security risk in the file, then such a message is meaningless.

I can guide you if you turn off this prompt, but please make sure that the source of all files downloaded from the Internet is secure.

1. Search for Internet Options in the taskbar and open it.

2. Click "Security" and then "Custom Level":
   

3. In the displayed page, find "Launching applications and unsafe Files (not secure)", then click "Enable", then click "OK" to save the changes.

    

Now, you should not see this message anymore.

If you are a Windows User, I can actually recommend that you try changing the UAC (User Account Control) Settings.

Search for UAC in the taskbar and open it. Drag the slider to "Never Notify" and click "OK."

Once this is done, many user account control prompts will no longer appear.

Found here: How to Turn off "Open File - Security Warning" message for a specific - Microsoft Community

You cannot use an ICO file that is located on a network folder (It must be on a local drive), otherwise it will not show. This is for a mapped drive or a UNC folder.

There are 2 ways to fix this issue. Group Policy or Registry entry.

Found here: Shortcut Icon blank when .ico file is located on a directory defined with an UNC Path - Microsoft Q&A

We found that doing the following worked, and can now edit the settings in the II6 Manager without errors (and without crashing when applying settings) every time:

1. Stop SMTPSVC service [Display Name: Simple Mail Transfer Protocol (SMTP)]
2. Stop IISADMIN service [Display name: IIS Admin Service]
3. Edit "C:\Windows\System32\inetsrv\MetaBase.xml"
4. Find: <IIsSmtpServer Location ="/LM/SmtpSvc/1"
5. Add (Settings are alphabetical): RelayIpList=""
6. Save file
7. Start IISAdmin Service
8. Start SMTPSVC service

You can now open the Internet Information Services (IIS) 6.0 Manager (InetMgr6.exe) and work like normal. The setting above relates to the Access Tab > Relay Restrictions section, but doesn't set anything in it (i.e. "all except the below list" with a blank list).

After setting this value you can change it to what you need it to be. (i.e. the value doesn't need to be 'null' for the fix to work, just so long as the variable is present in the file).

The above has been tested on a few new installs of Windows Server 2022, and has worked for us every time. If you have done an upgrade there are some other things to consider (seems like the SMTP service is not installed after upgrade so will require a backup of the settings that can be applied post reinstalling the service. But that is discussed in other topics).

PS: Remember to set the SMTPSVC service to start "automatically". By default its set to "manual".

Also Here: How do I resolve the "Snapin Error" when setting up SMTP on IIS Server? - Server Fault