change Received-SPF

Hi,

Since we don't have money to use an smtp server (emails are non-commercial) we are trying to find a cheap way to send them emails. We are currently testing sendblaster direct send. The problem is that some isp reject the emails because of Received-SPF not beeing correct (we are sending the messages from a home computer of a member).
I would like to ask if there is a way to change the Received-SPF in sendblaster or if I can use an other software to do that.