You are reading this article becasue you need to know what the SPF settings are for Rackspace Mail
What is SPF?
SPF is short for Sender Policy Framework. Its a system designed to help validate legitimate senders. When you add SPF information to your DNS records, you are able to specify the email servers you use to send email from your domain. This validates your sending email address, which can improve your email deliverability rate. In other words, SPF helps to keep your domain’s email out of your recipients’ spam folders.
Your dns record should have the following spf record to work with the Rackspace Mail service.
"v=spf1 include:emailsrvr.com ~all"
This is usually added as a TXT record in your dns settings as below.