There are few ways to do it. One of them is to use blat. Another one is VBScript. Here is example of such vbs:
Set oShell = CreateObject( "WScript.Shell" )
user=oShell.ExpandEnvironmentStrings("%UserName%")
comp=oShell.ExpandEnvironmentStrings("%ComputerName%")
Set objEmail = CreateObject("CDO.Message")
objEmail.From = user+"@"+comp
objEmail.To = "your-name@your-email.com"
objEmail.Subject = comp + " RMAN backup failed"
objEmail.Textbody = "Please check RMAN log file"
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") = _
"your.smtp.server.com"
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25
objEmail.Configuration.Fields.Update
objEmail.Send
user=oShell.ExpandEnvironmentStrings("%UserName%")
comp=oShell.ExpandEnvironmentStrings("%ComputerName%")
Set objEmail = CreateObject("CDO.Message")
objEmail.From = user+"@"+comp
objEmail.To = "your-name@your-email.com"
objEmail.Subject = comp + " RMAN backup failed"
objEmail.Textbody = "Please check RMAN log file"
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing") = 2
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") = _
"your.smtp.server.com"
objEmail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") = 25
objEmail.Configuration.Fields.Update
objEmail.Send