Why it works
The human brain has an innate drive to resolve questions and close information gaps. Creating a small, safe mystery encourages the reader to respond just to find out the answer.
Example
I found a way to double your current output, but I'm not sure if it's the right fit for you.
An illustration of the mechanism, not a template. Copied verbatim it stops being persuasion and starts being the pattern everyone else is already sending.
Is your sequence pulling this one?
Paste it in and find out which levers are working, which are missing, and which single zero is capping the whole message.