Depends who is asking.

Let’s assume a scenario where you are trying to create a new self-signed certificate on Exchange 2007 using a script. You run the command “New-Exchange Certificate – Services “IMAP, POP3, IIS, SMTP” –Confirm:$false”. The script stops at a prompt when it tries to confirm overwrite of existing SMTP certificate (because current self-signed certificate is assigned to that function). Since this is breaking your script, you decide to throw in –force to force override of the prompt.

Now you face another error: “Parameter set cannot be resolved using the specified named parameters.

This is because –Force serves different purpose in Exchange 2007. According to TechNet:

Use this parameter switch to overwrite an existing certificate request file that matches the same file path as specified in this cmdlet. By default, this cmdlet will not overwrite existing files.

Unfortunately, there is no way you can override the dreaded SMTP certificate prompt in Exchange 2007 (that I know of).

Now let’s turn our attention to Exchange 2010. Since New-ExchangeCertificate cmdlet does not directly write to a file, –force serves the purpose you expected in previous scenario. According to TechNet:

The Force switch specifies whether to override the confirmation prompt and set the new self-signed certificate as the default certificate for TLS for internal SMTP communication. By default, this cmdlet requires a confirmation before setting the new certificate as the default certificate for TLS encryption of internal SMTP communication.

So in case you were wondering, there you go.