All emails sent through Reamaze are signed by Reamaze and originate from @reamaze.com for best deliverability. By default, you should not have to alter your domain's SPF records for deliverability purposes. However, if you'd like to ensure this even further by adding Reamaze to your SPF record, you can add an entry like "include:_spf.reamaze.com".
For example, the following is an example of a valid SPF record:
v=spf1 a mx include:_spf.reamaze.com ?all
For more information about the SPF syntax, please see the documentation on openspf.org.