Problem with MX DNS

Guys, I'm new in Linode and It is the first time I need to configure this kind of parameters. I trying to configure MX DNS but it is not working. The parameters sent by the webmail server support are:

Type:: Txt

Name: With out name (empty)

Data: v=spf1 include:spf.redehost.com.br ~all

Type: Mx

Name: With out name (empty)

Data: lmx.antispam.redehost.com.br

Preference: 30

Type: Mx

Name: With out name (empty)

Data: fmx.antispam.redehost.com.br

Preference: 20

Type: Mx

Name: With out name (empty)

Data: mx.antispam.redehost.com.br

Preference: 10

But it's is not working. Ther is no way to make an empty register in MX DNS, it is necessary to use fill with something them I'm using mydomain.com.br but I'm not sure if it's correct because i didn't find this kind of information in documentations.

Please, help me with this issue. Thank you very much!