OK, it should support setting sender, so try this, after the code below in the cdosys part of inc_mail
objNewMail.To = strRecipients
objNewMail.From = strSender
objNewMail.Subject = strSubject
objNewMail.TextBody = strMessage
insert the following line immediately below it and before the send command.
objNewMail.Sender = "AN EMAIL ADDRESS THAT IS VALID ON YOUR MAIL ACCOUNT"