In WHM, go to Edit DNS Zone and select the domain you want to add an SPF record to.
Then add a new entry as follows:
Code:
domain.com. IN TXT "v=spf1 a mx ~all"
It should be obvious where the components of that line need to be written.
What this actually does:
Code:
v=spf1 This identifies the TXT record as an SPF string.
a Indicates the A record for your domain can send mail, in other words
the xilo server on which your domain sits can send mail for your domain.
mx This allows the MX records for your domain to send mail. Normally this
actually equates to the same server as the A record but not always. Its best
to include it in case your domain has a slightly different setup.
~all Essentially means only servers specified above can send mail purporting to
be from your domain.
As always if you need anymore help, post up here.