The representative sent back an obvious copy-paste. Could've been the response to any email about the topic, and sounded like a campaign pitch.
The senator (or at least a staffer) replied with reasoning. I didn't agree with the reasoning or conclusion, but somebody definitely read my email and responded specifically to it. I appreciated the respect they showed that way.
They voted opposite of what I requested, then wrote back giving a synopsis of the bill and mentioning it passed without even mentioning their vote against the bill.
There is nothing you can do if you live in a "safe" district.
If you live in a contested district, donate to their opponent, and send them a copy of the check, so that they can see it before they read the letter.
Some interesting stuff here:
https://www.wired.com/story/opengov-report-congress-constitu...
My representative called me to talk about it. He told me he hadn't seen the bill but he agrees that isn't where the FBI should be spending their energy. It seems like the bill never got off the ground.
My guess is the prewritten letters are probably less considered.
This is a while back, now, but I vaguely remember a Reddit AMA by people working for US federal politicians where they indicated that "big enough" is often as few as two for the right type of correspondence (bespoke letters and / or letters to the editors of voter-relevant newspapers, especially if the politician get specifically called out)
Things may well have changed in the interim, but given how often engagement begins and ends at signing on to a form letter, I wouldn't be surprised if this was still the case today.