Depends on the politician. A few years ago, I wrote emails to my US House representative and one of my senators. They didn't come from a template. I wrote a few short paragraphs stating my wish, my reasons, and a bit of praise for something they recently did.

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.

Wrote to a state legislator regarding a specific bill.

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.

One time they sent back a letter assuming I opposed a position that I actually supported. In fact, I think the senator supported it too, but probably only got letters from people opposing it.

That's because voting literally doesn't matter. At all: https://represent.us/americas-corruption-problem/

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.

No. But staffers do.

Some interesting stuff here:

https://www.wired.com/story/opengov-report-congress-constitu...

The EFF sent me a letter encouraging me to contact my congressman to support a bill that would prevent federal funding of anti-encryption technologies by the FBI. (https://act.eff.org/action/speak-up-for-strong-encryption-ru...)

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.

They almost certainly do not. However they do count them (well, maybe the intern counts them, but they are counted). And if the counts get big enough, they do start paying attention.

> And if the counts get big enough, they do start paying attention.

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.