I always call and confirm that I will be onboard. It's habit by now. I don't think it has anything to do with the TSA- I've been doing it as long as I can remember. The one time I forgot was for a flight from UK to the USA and nothing happened.

Occasionally the flight times change too. This happened to my parents when flying LAX to LHR. The flight was moved by a couple of hours (I forget the reason).

Ooh, I didn't know you were supposed to. We didn't confirm our return flights from New York in May and all was OK when we got to Newark - we just used the self service check-in

I have been flying with Lufthansa 1-2 times per year for the last 30 years and haven't had to confirma flight for over 20 years now.. I am booked with them to fly to New York next year and my booking email doesn't say anything about confirming though I do check on the Internet a few days before flights to see if there are any changes, departure times on International scheduled airlines rarely have any substantial last minute changes. I flew round the world a couple of years ago with meant using four different airlines and didn't need to confirm any of the flights. Charter companies often change flight times though so it is worth confirming their flights if requested to. Some Far Eastern carriers request confirmation (can't think of the names though) as they have long standyby lists and may give the seat away if it isn't confirmed. But with Lufthansa you don't have a problem.

But the original post states that she has rec'd an email from Lufthansa requesting confirmation be done...... I would follow those instructions and then ask for details once you get to check-in.

Just asked at my local Lufthansa office and they said no need to confirm flights unless part of the journey is with another airline. They also said that often if flights are booked through another agency (in this case lastminute.com) then the agencies use a blanket format on emails which will advise all their customers to confirm.
Kilgoreck you won't lose your seat if you don't confirm but if it gives you peace of mind go ahead and do it as you probably will want to check if the times are correct.
Was the email from Lufthansa or Lastminute.com?

Well. Didn't bother checking with Lufthansa on way back and low and behold there was a message on my mobile at 10:00 in the morning from Lastminute.com saying that due to operating difficulties the airline had cancelled our 18:55 flight and rebooked us on the 13:55! There must have been a lot of people who couldn't be contacted who turned up for the original time so God knows what happened with them. The irony being it actually states on the email they sent me for new flight that yodidn't need to reconfirm flights!!

Guess you should double check then!

Wow! That was lucky. I give my mobile number but as it's a work one I never take it on holiday!! I'd have been stuffed. Lesson learned for me.

I'm flying to New York with Lufthansa, I hope they don't change the time of return as although they have my mobile number it's not a triband phone so it won't work it the USA. Still if they will put me up in a hotel for an extra night I won't be complaining

We were told on our tickets to canada to do this and when we rang the number on the ticket the girl at the other end knew nothing about it!