That hit everything that I was missing. I'm not your customer but I HATE piecing together multiple emails and email threads into a cohesive document.
Your biggest benefit is letting people focus on their business rather than chasing documents down and organizing disparate emails/communications.
Write from that perspective and I think you'll connect with your customers.
This is a bit long but it captures the emotion and puts the reader in the scenario that you are trying to solve:
"Wouldn't it be great if you could finally focus on your work, instead of pulling your hair out while hounding your clients for documents that they should have sent last week?"
One benefit to this style of headline is that it relates to your customer and puts them into the "Yes" mindset right away.
If you don't like the question approach, try something like:
"Imagine if you could finally focus on your work, instead of pulling your hair out while asking your clients for documents that they should have sent last week"
Same effect. It addresses the problem. Following up on document collection is a pain in the ass. Our system will handle it for you.
Follow up with a sub-headline that talks about having to stitch together multiple disparate communications to really illustrate the pain of dealing with this.
Then, write about the benefit to using your automated messaging, etc.
All of that copy should be guiding the user down to the sign up.
Once you nail that user journey, then focus on whatever design needs you have.
Hope that helps.
Good luck and I hope this takes off.