I'm guessing you are a newly hired executive for this company. You've said it's a distributed company, with your fellow executives rarely meeting face to face. My answer assumes those facts.
As an executive, one of your most important jobs is to shape the company's culture and decision-making processes. (I'm not saying you need to build a massive decision-making infrastructure with vast documentation, quite the opposite.) You and the rest of your leadership team need to be able to handle decisions nimbly, and in most cases you need to be able to decide and move on.
It sounds like you're used to an email-thread style of decision-making discourse. That's a workable scheme, but everybody has to participate, and they aren't right now. So, if you keep trying to "push that rope" you won't get very far.
I am guessing your co-workers have another way of making decisions, and you haven't quite figured out what it is yet. That's not a criticism of you: these things grow up organically, especially in small distributed companies, and your colleagues may not be conscious of how they do this kind of work. It's also possible they do it badly.
Have one-to-one conversations with your fellow leadership team members. Ask each of them directly, "how did you make a critical decision?" Work through a recent example. An obvious one is "how did you all decide to hire somebody into my position?" Make it clear that you're asking so you can learn how they work together, not to challenge them. Any recent decision, or maybe even a decision that's currently being made, can be an example.
Be careful not to ask the totally abstract question "how do we make decisions?" You care about how these folks actually decide things, not about how they think they should decide things.
If your function in the company needs to make lots of decisions, you may need to start shaping the executive culture very intentionally. You may need to insist on a weekly Skype teleconference or some such thing, with a formal agenda of "decisions we need to make this week / next week / this quarter" etc, and work out a way of making those decisions together or visibly delegating them. This doesn't have to be hard. But you and the leadership team are jointly responsible, even for delegated decisions, so you need to have some dialog about them.
If you're not the CEO you need the CEO to help drive this. If you ARE the CEO you need to get buyin from your colleagues. Do keep in mind that some of the early executives in startup companies aren't really cut out to remain executives as the company grows. If somebody refuses to play along, you may need to grow the company around them.
Go read The Fifth Discipline by Peter Senge.