Speeding ticket in Italy

I am not sure how to help you, but just had to say how refreshing it is to read a post about a speeding ticket in Italy where you aren't complaining about the scam that has been perpetrated on you!

Maybe try contacting the rental car agency? They would have assisted traffic enforcement, so maybe they have kept some record of it?

I'm sure you noticed a $40 or so service charge from your car rental company for an administration fee to tell the city who and where you were.
The city wants you to wire transfer the funds directly into their checking account, and they give you their routing number and account number. And they want the money in Euros, not American dollars.
There are bill pay services online in Europe that can charge your credit card in dollars and forward the money for you. And their service charges are actually pretty fair
I was hit for a fine by a radar camera going over the causeway to Venice for 1.8 mph over the approximate 35 mph speed limit. There is no variance by those heartless cameras, and they're strategically placed.

You can use on online translation service, eg Google translate, to get a reasonably accurate translation - not perfect, but usually close enough to understand (use Google's Chrome browser and it should offer you the option to translate the web page to English).

Pay your ticket. It's not worth the hassle of trying to dodge it (and they got you legitimately).

If you must wire them money, consider using TransferWise (TransferWise.com). It's easy and not very expensive (much easier and much cheaper than going through your bank). I've had good experiences with them.

For my Spanish ticket, I was able to find the website to pay it online and it was easy. For a German ticket that had no website, I figured out how much the ticket would be in dollars, added a couple dollars for exchange rate fluctuations and sent the municipality a check in dollars. They cashed it.

As far as implications if not paid ; assuming you are unable to track the details down and never pay.
No one really knows if at some point that could affect your US driving record / credit report ; probably not but some risk there.
You may get some debt collectors calling/mailing threatening these actions but as to their actual ability to get it onto your record is questionable.

Returning to Italy ; you surely won't be stopped at the border or by immigration for it.
Likely your rental car company does not access such records so likely can rent a car still.
IF you were pulled over by the police ; random checkpoint, infraction or involved in some kind of accident then yes you could find yourself in real trouble with an unpaid ticket on your record ; though not sure if different cities/towns networks are connected throughout Italy.

Point being if you plan on returning to the country and renting a car there it would be wise to get the ticket paid.
It is of course the right thing to do, even if not willfully, you did break the rules, got caught and should pay the fine.

This happened to my son while in Switzerland last year. The ticket came 9 months after the fact. I'd like to know how many local citizens in those countries get ticketed for going 2 - 10 over the limit. It's hard to believe an Italian citizen is going to get bagged going 3 or 5 over! Seems like a scam aimed at tourists...

Thanks for all the advise. I have contacted the rental car company so hoping to hear back from them. We definitely want to get the ticket paid, not looking to get out of it by any means.

It's hard to believe an Italian citizen is going to get bagged going 3 or 5 over! Seems like a scam aimed at tourists...

Why? What's this opinion based on?
Do you think that speed traps can magically understand when the driver is italian and stop working?
I wonder What's also hard to believe in your world, I don't know... that different doesn't mean deceitful?

Incidentally, there is a minimum 5 kms/h leeway, so the OP was going at least at 10 kms/hour over the limit.

hoping to hear back from them

The rental agency gave your name to the cops and the cops sent you a registered letter with the fine that you did not appeal or pay.

What could the agency do now? And why?

From the day you receive a fine via mail, you have 60 days to pay or appeal. You didn't pay. If the 60 days have passed you may receive another couple of letters in the future, but cops in the long run always close the file and sell such debts to an international collection agency.

Dario, Here’s why so many US-based people mistakenly think a ticket is a scam: we treat our speed limits like suggested minimums, so newbies think the rest of the world is based on the American model. It’s not.
Culture shock, naïveté and projection that the other is out to get tourists rather than assuming responsibility for being even 1 kilometer over the limit. Thank you Shannon for your refreshing post! We see so many crying scam.

Obviously the Italian drivers don't get bagged because the robocam can see they are eating as bowl of pasta as they exceed the limit.