What does the following SPF record allow?

v=spf1 ip4:211.121.22.56 a mx a:server.hostname.com ~all

My understanding is it allows the following to send out emails:

ip4: 211.121.22.56

a: A recor开发者_如何学Pythond (where website is hosted)

mx: whatever the MX record says

a: this server name

And nothing other than the above 4 places

Am I correct?

I don't know about the "a"s but yes, it validates to whoever checks it - that mail is allowed to be sent in this domain from either the IP address or the server.hostname.com.

Q. Should be on serverFault.