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.

yourdomain.com's IP address is 208.87.33.150. Does that server send mail from yourdomain.com?		yes no
This wizard found 2 names for the MX servers for yourdomain.com: nullmx.catholicfcu.com and nullmx. (A single machine may go by more than one hostname. All of them are shown.) MX servers receive mail for yourdomain.com. Do they also send mail from yourdomain.com?		yes no
Do you want to just approve any host whose name ends in yourdomain.com? (Expensive, unreliable and not recommended)		yes no
Do any other servers send mail from yourdomain.com? You can describe them by giving "arguments" to the a:, mx:, ip4:, and ptr: mechanisms. mx: takes domain names and approves all the MX servers of these domains. To keep the wizard short we left out ptr:, but it works analogously.		regular hostnames
		domain names
IP networks can be entered using CIDR notation, eg. 192.0.2.0/24		IP addresses
Could mail from yourdomain.com originate through servers belonging to some other domain? If you send mail through your ISP's servers, and the ISP has published an SPF record, name the ISP here.
Do the above lines describe all the hosts that send mail from yourdomain.com?		yes no
yourdomain.com. IN TXT "v=spf1 ~all"

The SPF record:

v=spf1 -all

can be explained as:

	v=spf1	This identifies the TXT record as an SPF string.
	-all	No servers are allowed to send mail from yourdomain.com. This is appropriate for web-only sites.

You need to transfer these records to your DNS server by yourself. No changes can be made by the wizard, it can only provide you with the data that needs to be entered into your DNS server.

yourdomain.com. IN TXT "v=spf1 -all"

'yourdomain.com:v=spf1 -all:3600

If you run Windows DNS

Please see these instructions.

More options

If your site requires more complex configuration than this, you should read more about mechanisms. You should also review the tradeoffs involved in choosing an "all" default: see page 15 of the white paper.

You can test some pretend scenarios at one of the DNS tools. MTAs that reject mail because SPF tests failed will link to the why page.