Stationery might be an endangered species, with engraved invitations on the wane and even postcards with who, what, when and where being replaced by electronic invites.

Evite is the biggest online party animal, used by millions to host baby showers, wine tastings, birthday parties and high school reunions. Competition is growing among others such as Socializr, pingg, Center’d and MyPunchbowl.

Even Lizzie Post, great-great-granddaughter of etiquette maven Emily Post, says e-invites are OK.

“I think they’re acceptable, but that depends on the party you’re throwing,” she said. “For a wedding, no. For a major gala event, no. For a holiday ugly-sweater party, yes, I think they’re great.”

Post, 26, hasn’t actually used Evite or its ilk for her own parties, but she says that given how few guests bother to RSVP by phone, “this may be the only way to get people my age to respond.”

OK, fine. Yet these electronic requests have a feature that draws a raucous conga line between the generations: Each lets invitees eyeball the guest list before deciding whether to attend — or to ditch these losers.

Guests then reply yes, no or maybe (more on that option in a bit), with a comments box where they can elaborate for everyone else to read.

From Evite’s perspective, it’s simply social networking. “The banter starts on the invitation, giving people a way of saying, ‘Let’s get this party started,”‘ says Lariayn Payne, vice president of marketing and public relations for Evite, based in Los Angeles. “This lets you RSVP with a bit of explanation that you might like to give the host.”

Payne allowed that comfort with such disclosure varies among generations. “People who are more into social networking really like having their comments out there and known,” she says.

Still, the public guest list fosters a collision of human nature, etiquette, technology and privacy. Just because something is viewable, should it be? And where does a host’s transparency and a guest’s self-interest overlap?

Post says that if the choice were hers, she would disable the function that shows the guest list. “It’s not OK to decide whether or not to go to the party based on who’s going. You would never ask the hostess, ‘Oh, who else will be there?”‘ she says.

And her other pet peeve is with the “maybe” option. “I’ve had friends who ‘maybe’ me all the way until the day of the party, and I finally say, ‘You know, I’m counting you as not coming.’ It’s not nice.”