Sorority Rush Process

I just want to make sure I keep my options open and am aware of how the process works. I heard it's very common at smu for a lot of girls to be dropped from sororities and that a lot of it is connections-based. I hope to maximize my chances and have no regrets.

It's not quite true what you are asking "Is it true that sororities can only vote on you if they know you?"
First of all, every sorority chapter has it's own voting process as dictated by their nationals, there's no SMU way of doing things, and chapter members only know how their sorority does it not how other sororities do it. But they are all fair and all sororities rank every pnm from round to round.
What you are probably actually talking about is that in early rounds, for some sororities, members only vote on the pnm's they were assigned to talk to. Every pnm meets the same number of actives in a round so it's not a bad way to do it. In others, all members rank all pnm's, but the members who met a pnm will give their opinions and then everyone makes her own ranking (respected chapter members get listened to).
You can't do a thing about how a chapter votes on their pnm's.
Another thing to consider is that connections rule. 60% of students come from in-state and that means that pnm's coming from Texas schools and hometowns will already have friends in the chapters. There are also similar pockets from Atlanta, other Southern cities, Cali, Florida, and a couple of other areas. Sorority members are ALWAYS going to prefer the girls they know over those they don't, no matter how high the GPA or stellar the resume. Don't worry about something you can't do anything about, but do get recommendations for every chapter because it will hurt you to not have them. It won't help to have them, but it will hurt if you don't, if that makes sense.
Grade cuts come during the first round and can be brutal. You have good grades? Well so does everyone else. Ditto for your great resume. You're in a different peer group now where everyone's special.
Another thing for you to know is that every chapter is given a limit by panhellenic of how many pnm's they can invite back each round, and they can't go even one over that number. That means that houses that are very desired, especially among the Texas girls, will have more pnm's wanting to return to them than they can invite back, and so their cuts are heavier. They could have liked you a lot but they have a cut-off. It's a numbers game.
When a chapter does not invite you back, it is not personal and it doesn't mean they didn't like you, or that they thought you were unworthy, or that they wouldn't want to be your friend. Rush is a numbers game. If you feel that you made a real connection with someone who was rushing you, it's probably true and she loved you back, but if you get released from that sorority, understand that she is only one vote within her chapter. You have no idea what is going on in chapter voting and the effort that members put into pulling for their favorites. You might have just missed their cutoff. It is a chapter decision, but know that there are probably some members in tears over losing you.
Finally, there are no bad chapters at SMU. You are not better than the members in any house.

How come they dirty rush so much if it’s considered a fair process? If it was fair then they wouldn’t dirty rush girls, they’d just wait until they get there. I get that people may already have friends but rushing new girls over the summer is so unfair because some girls go to smu and want to join a sorority to make friends and have fun but can’t get in due to lack of connections (as they mainly recruit friends or pre-rushed girls). And it’s not fair for pnms to join a sorority they don’t connect with at all since they have no shot at some of the mid and top sororities without preexisting connections.

SMU GDI Crisis Office 😵

There is a large number of newly ShOcKeD GDIs in our dormitory this week. Several hundred of us. We are sHoCkEd, angry, depressed and resentful to the university and especially panHELLenic. 😨

Given it's long history for deceiving young freshmen PNM girls, the university and panHELLenic 👿 should immediately open a Newly ShOcKeD GDI Crisis Office to assist these emotionally harmed girls. 🛏

Cry more

You don't need a 'top' house you need a sisterhood that will lift you up. More pnm's are coming from out of state every year and looking more objectively at what each house has to offer and especially at the members of each house. Less and less do they care about kappa or pi phi because they don't need the in-state recognition for those particular letters. Pnm's are considering qualities like the personalities of the members they meet and how they are treated by them, academics, leadership, and accomplishments, and how the members interact with each other.