SIU cannot be that large a campus.
Instead of emailing, why not get to know some of the Ladys of the Soroitys.
I am sure there are some in your classes or you see on campus events. They are not snobs, but just women going to college.
Just to reiterate, there may have been many reasons for not getting a bid:
The need of the Chapter for certain areas.
Grades.
Participation with school events.
Coming off as to shy.
Quotas are a very big thing in womens Organizations.
There may be a myrid of reasons that were beyond your control!
Just go with it and see what happens.
Explore all of your options and good luck in your quest