<cfset var MyArgs = StructNew() />
<cfset MyArgs.To = "somerecipient@gmail.com" />
<cfset MyArgs.From = "somesender@yahoo.com" />
<cfset MyArgs.Subject = "Check out CF8!!!" />
<cfif StructKeyExists(arguments,"MailServer")>
    <cfset MyArgs.Server = arguments.MailServer />
</cfif>
<cfif StructKeyExists(arguments,"Username")>
    <cfset MyArgs.Username = arguments.Username />
</cfif>
<cfif StructKeyExists(arguments,"Password")>
    <cfset MyArgs.Password = arguments.Password />
</cfif>
<cfmail argumentscollection=#MyArgs#>
Holy cow!
</cfmail>