Why it works
People have an internal sense of reciprocity where they feel obligated to return a favor if someone has provided value to them. Giving something useful away for free creates a social contract that encourages them to reply.
Example
I have attached a free report on your industry benchmarks so you can see how your performance compares to your top competitors.
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.