Updated

Can’t remember if the fork goes on the left and the spoon goes on the right? For perfect P's and Q's, you know exactly whom to ask: Emily Post.

But what are the rules when you're talking with a friend and she whips out her cellphone to check her email, or when someone you never liked in high school suddenly wants to be friends on Facebook? Who’s there to tell you the right thing to do?

Once again, it’s Emily Post.

“The heart of etiquette and manners is how we treat each other. People are social animals and there will always be questions about how to behave. No matter how many devices we have, we still need each other,” says Daniel Post Senning, Post’s great-great-grandson and co-author of the recently released 18th edition of “Emily Post’s Etiquette.”

This latest edition of the classic, subtitled “Manners for a New World,” has more than the regular advice you’d expect from an etiquette book. It also addresses modern dilemmas related to new technology.

“Our shared communication environment has changed so much in the last five to seven years, and we felt it was time to have more than a cursory look at email, and time to acknowledge social networks,” Senning says.

The Posts have dedicated no fewer than seven chapters of the 722-page tome to communication and technology -- what they affectionately refer to as “netiquette.” The manners manual’s message is that etiquette is for everyone, not just the rich and fancy. Five generations of the Post family have developed guidelines based on the principles of respect, consideration and honesty, which have not changed since the book’s first edition was published in 1922.

Though most of the book is based on common sense, many of us violate the Post rules regularly. Among the most glaring etiquette mistakes regarding technology is the inappropriate use of cellphones and the Internet. Here’s one you’ve probably ignored: never interrupt a conversation to answer a call, email or text.

Here’s another: When in a suitable place to use a cellphone, watch your volume, tone and language.

The book frowns upon cellphone use in a place of worship, theater, or restaurant, or during a meeting or presentation. And if you’re expecting an urgent call, you should set your device to vibrate and check it later, or move to a private space and speak as quietly as possible.

What do you do when a call gets disconnected? According to Post, the person who initiated the call should redial the other person and apologize, even if it’s the phone carrier’s fault.

It’s hard to correct others who ditch decorum, but Senning says you can always try to set a good example. “The best way to effect change you’d like to see is to model the behavior,” he says. “Be really sure you don’t answer a call during dinner. Note at the start of the meal that you left your phone behind or decided to silence it.”

Other phone faux pas include typing, eating, shuffling papers or doing anything that tells the caller your attention is elsewhere. And never, ever “call from the stall”; nothing ends a conversation quicker than a toilet flush.

Regarding email, the book says you should always respond within a day or two to personal messages, and within 24 hours for business mails. It also favors checking with friends and family before forwarding spam mail such as chain letters, ads or jokes to make sure these emails are welcome.

Senning says the most common error people make with electronic communications is airing their dirty laundry, and he suggests people consider anything they email, text or post online to be a public document, fit for a community bulletin board.

“Everything you do online is public and permanent,” he says. “Don’t allow yourself to be seduced by the illusion of privacy. The places we interact with computers and phones -- our offices, our homes, our cars -- are some of the most private places where we’ve come to expect and deserve a little privacy. But at the same time, the second you turn on your computer and interact with the online world, you are instantly engaging the most public space.”

The explosion of social networking has brought up several new questions for the Post family. “Etiquette” says you are not required to respond to every person who contacts you on Facebook. “Human attention is a gift. Online spaces are very public and just about anybody can send you a friend request. You’re not obligated to a total stranger,” Senning says.

You also don’t have to continue contact with a Facebook “friend” after the initial reconnection conversation, and it’s perfectly acceptable to actively unfriend someone, untag yourself from photos, or delete a friend’s comment from your page. You are, however, obligated to ask permission before posting a friend’s good news or photos of an event. And if you want to post the death of a loved one on Facebook, make sure all of the deceased’s relatives and close friends already know.

There’s Twittetiquette, too. You don’t need to follow someone on Twitter just because they are following you. And put down that smartphone, flower girl: neither the bride, the groom, nor any other guest should be tweeting at a wedding.

The book further contends that human contact still matters, and it says people should talk in person whenever possible, especially to communicate important news-- like divorce, death, or job loss— because these matters require sensitivity that can be lost in an email.

What would Emily Post have thought of people choosing texting over talking and emailing over letter writing?

“This may come as a shock but I think she would have loved it,” Senning says. “Emily was an early adapter…and a new media personality on a very popular radio program. Whatever the new medium of her time was, Emily would be a participant. One of her gifts was her understanding of how some of these new tools would fit well into a social order.”

To underscore the Post family’s commitment to technology, you can find answers to all your burning etiquette questions on your smartphone by going to the mobile version of emilypost.com.

But, please, don’t do it in the theater.