Suppose I have example0.com as my SMTP server and example1.com as MX.
As you see, They're different with each other.
Scenario: If I send an email , and suppose receiver has an Anit spam such as SpamAssassin, Because example0.com differ with example1.com , Indeed SMTP deffer with MX type, Anti Spam consider a spam score for email being send?
If you set your SPF record to specify the server use something like this to generate your SPF http://www.spfwizard.net/