Most domains send outbound mail through a relatively small number of servers. Domains should describe that set of servers in an SPF record in their DNS. Internet email receivers can then reject forged messages which don't come from an envelope sender domain's approved servers. This wizard helps domain owners identify all the servers which could be expected to send mail from their domain.
Source: http://old.openspf.org/wizard.html?mydomain=&x=33&y=7

ok thats it for now from me, hope this see more helps those who are needing this information.