I am sorting out an itinerary for a trip to Italy in late May. We have a flight out of MXP on Sunday 5/31 @ 10:20 am. Is it possible to get from the Lake Como region (potentially Bellagio) to the airport without a car? Or do we really need to come into Milan the night before our flight?

Are you willing to hire a taxi?

Assuming you would need to be at the airport no later than 8 AM, you'd be beholden to the ferry schedules to get you to Como in time to pick up the next transport option to MXP. It's not a short ferry ride, even the fast service is roughly 45 minutes just to Como.

Other options would include staying in Como the night before - you could take the train in the morning or have a car hire ready for you. That would shave 45 minutes off the commute and Como will certainly keep you entertained for the last evening. You could even go for a seaplane ride that evening, weather permitting.

You could also just have a car hire option ready for you, full stop, from your hotel on Lake Como and just get in and relax and let the driver take you. You'd leave quite early from mid-lake however to get to MXP before 8 AM.

There must be a faster way (hire car service?), but you can consider ferry to Varenna, train from Varenna to Milan and then airport shuttle from Milan Central.

I think the airport shuttle should run early enough, but I'm not sure about the ferry or the train, since this will easily take at least 2 hours.

ps. I typed too fast. I had "Bellagio" on the brain.

If you are in Varenna, you have the train station right there. It's an hour to Milan's central station, give or take - not the airport, the main station in town.

You could also ferry to Varenna from Bellagio and take the train. Overall though I'd avoid boats to get out of town that early in the morning. They are beautiful and it's fun to relax and see the beautiful scenery - but it's not rapid transit. (Unless you don't mind getting up extra early)

I just checked, and there is a 6:21 train out of Como that gets to Malpensa at 7:37 (via Saronno). So, if we spent 2 nights in Bellagio and just moved down to Como for our last night, this would be feasbile, correct? It would only be a minor inconvenience to change hotels, versus schlepping all the way to a Milan airport hotel.

I assume the trains are reliable in Italy? (Are they as punctual as the Swiss trains?) And does anyone know approximately how much a car to the airport would be from Como?

A car to the airport from Menaggio is about 160 euro. Como is quite a bit closer to the airport.

I had a friend share this horror story with me.

She had to catch a flight out of Fiumicino in Rome. She was in Florence. She figured that she'd catch the Florence-Rome Express (Eurostar) the morning of the flight.

Except she got delayed on the train by a couple of hours. She missed her flight and had to buy a brand new ticket.

And this is Eurostar, so you figured that it'd be reliable. Not in this case.

So mishaps do happen. It just depends on how close you want to cut it. I had an experience myself (not with the train) but with the SAS coach in Oslo. I was going to the airport and there was an accident on the highway. I'm pretty sure that if I had taken the next coach, I'd have missed my flight. Obviously luck plays a role since I'm normally cutting it close, but that time, for whatever reason, I took an earlier bus.

One thing is for sure -- your departure being on a Sunday, there is no early morning bus or boat from Bellagio that would enable you to travel to the airport the same morning. It could be done on a weekday (e.g. taking the #C30 bus at 5.55), but not on a Sunday.
It's your choice whether you should overninght in Como or near the airport, or rather invest in a private transfer from Bellagio.