Have you ever tried to use outgoing blocking in Smarter 4.x ? It's new feature in Smatermail which helps you to control the outgoing emails. As you know, smarter uses different weights in order to calculate the final score of an email.
I selected checking SPF record for outgoing emails. After it I could send any email by using outlook and webmail! And I had to use webmail on server!! Checking logs shows this error :
Fail - Senders IP is NOT valid for senders domain (weight : 30)
I changed SPF record in zone file and it didn't work ! Finally I found that mail server checkes my primary IP and when I use outlook to send email, SPF checker detect my IP and I can't send email at all! Now the question why SmarterMail uses SPF checking for outgoing email s blocking, with knowing this point.