If I was a politician I would read through the electoral register for my area, or rather I would have one of my staff do so.
Why? well it might sound “political” (soc) but I don’t think I would reply to correspondence from non-constituents. After all why bother? they won’t be voting for me in the next election, they can’t!
I’ll now remove my tongue from my cheek and reveal I’m not serious, but I do believe this is what some politicians do. After all these days they must get so many emails they must have to have some system for weeding out the worthy ones from the unworthy. I imagine that Councillors don’t weed, as non Irish citizens can vote in local sections, so someone not on the electoral register could be registered, but surely TDs must check the register. I wouldn’t be surprise it there wasn’t a program to do it automatically. Possibly an add-on to Outlook, or some stand alone “case managment” software.
However I at least hope that politicians read their emails, because they reflect what the public are thinking. The public suggest ammendments to Acts, and silly red tape.
I imagine that the appointed Senators have no incentive to check the register, and perhaps that is why when I have had occasion to email politicians Senators rarely reply, TD’s usually do, and Councillors always do.

I know that if you go to some TD’s for help they will check the electoral registrar and if you aren’t on it, they’ll tell you to register before they will help you. There’s no point helping out people who can’t even vote for you. It encourages people to vote so I guess it makes sense!