DEAR MISS MANNERS: If you send an email to a business or company asking which department or individual handles a specific matter, is it polite to send the person who answered your email a thank-you for the information?

I know it's polite to thank someone in person who points you in the right direction to have your questions or concerns taken care of, but what about email? I don't want to clutter up someone's business email inbox, but is it rude not to thank them for the information they provided?

GENTLE READER: Although email etiquette is evolving, Miss Manners still believes that a service rendered deserves a thank-you.

She realizes that saying so will clutter her own email inbox with truculent explanations that everyone's email load is already burdensome; that if every transaction required a thank-you, the internet would be overwhelmed by the increased traffic; and that as a thank-you contains no new information, it is a waste of resources.

Yet she believes that a society that treasures endless social media posting, mass forwarding of jokes, countless customer satisfaction surveys, and other correspondence of questionable value, has no basis for objecting to a two-word email expressing gratitude and satisfaction. Not every transaction requires a thank-you in email, any more than it does in person. But it is perfectly correct in the situation you describe. Unappreciated thank-yous can be deleted in an instant.

DEAR MISS MANNERS: My mother corrects my grammar at home, but also tells me it is impolite to correct other people's grammar in conversation. Should I point out this discrepancy in instruction to my mother?

GENTLE READER: You would be asking for another correction, Miss Manners warns you.

Correcting a child at home is called child rearing. Correcting others is rude.

DEAR MISS MANNERS: What are we to do with a boorish dining companion, part of a group that dines out regularly? When seated with her (which sometimes cannot be avoided), we watch her treat the wait staff poorly, making rude faces and demands.

She expects nothing short of perfection wherever she is, including at pizza joints. She is quick to criticize the smallest infractions, like a waiter putting a soup spoon in the wrong place on the table.

We like the wait staff, try to be appreciative, and have no idea whether we should confront our colleague about her behavior.

GENTLE READER: Your boorish dining companion clearly does not expect perfection when it comes to good manners. Putting the soup spoon in the wrong place, whether in a Michelin-star restaurant or a pizza joint, is nothing compared to the rudeness of pointing out another's mistake.

Other than ostracizing the offending member, Miss Manners counsels you to make it clear that you do not condone your companion's behavior, but without yourself being rude. Studiously studying your shoes or your plate, being yourself exceptionally gracious to the wait staff, and perhaps also tipping well are all proven ways to distance yourself from your companion's rudeness.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I have never heard of "Call or write if you do not wish to attend" when I receive an invitation. I have always understood RSVP to mean "Let us know by such and such a date if you plan to attend."

There is no mystery if you do not reply by the date mentioned, as that automatically excludes you from the invitation list. No muss, no fuss, no need to write or call and say you cannot make it. The host automatically knows that all who plan to attend will have sent in an RSVP by the specified date.

It is also more "feelings" friendly, as you need not offer an explanation as to why you choose not to attend. You may not like the people, or you may have a previous engagement. By not replying, you do not have to hurt or ruffle feelings.

It adds no burden whatsoever to the host, as by the deadline, they know how to plan their event, as they know exactly how many people are attending. It saves time (and maybe feelings) for both the invitee and the host.

GENTLE READER: Do you have any idea how much havoc and hurt you are causing? You and everyone else who hold the bizarre and callous notion that people who are good enough to offer you hospitality may simply be ignored?

Even the most casual invitations require definitive replies. If a co-worker stopped by your desk and asked if you'd like to go out for coffee, would you just turn away without a word?

About the workability of what you suggest, Miss Manners assures you that you are wrong. She is flooded with mail from anguished hosts who find that people who have not responded to their invitations may nevertheless show up -- and those who have accepted may not. (The same is true of the odd but common directive "Regrets only," which you claim does not exist.)

Hosts' feelings are also something Miss Manners knows about. People who entertain are not so naive as to believe that everyone can or will attend. But they are insulted not even to receive the courtesy of a reply.

No excuse for declining need be given -- just an expression of gratitude for the invitation and regret at being unable to accept.

DEAR MISS MANNERS: We are a gay couple who have been together for 24 years. We always hoped that someday we could be married, and now we can.

Since we have been together for so long, we really don't need linens, china, etc., so we have requested that in lieu of gifts, guests should please consider making a donation to one of three chosen charities.

Well, the bills are piling up, and I've got a severe case of sticker shock. (Weddings are expensive!)

I sense that some relatives might try to write checks to us as gifts, regardless of our request. Would I be a hypocrite if I accepted them? It's starting to look like we really could use the money.

GENTLE READER: Take it.

Miss Manners will spare you her distaste for soliciting presents, even on behalf of charities, and also for making payments instead of giving presents. If people decide by themselves to give you checks that are not directed toward charities, you should accept them graciously.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I'm in college and work as a customer service representative at the campus copy and print shop. Frequently, customers will come up to the counter wearing headphones and will not remove them or pause their music while I discuss their order with them.

Although I always try to be patient with customers who do this, it frustrates me, and I consider it rude and disrespectful. It makes the transaction take much longer, because I will need to repeat questions and explanations several times (since these customers aren't able to hear what I'm saying).

Is their behavior out of line, or am I just overreacting? And is there anything polite I could say to try to correct this situation, or should I just continue to smile and repeat myself in the most pleasant tone I can manage?

GENTLE READER: Why say anything at all to people who are obviously not listening?

You could just stand there smiling and waiting expectantly. When the customer inevitably demands why you are not speaking (and with any luck, takes off those headphones to see what is being missed), Miss Manners would say, "Oh, I was afraid that you wouldn't be able to hear me, so I was waiting until you were ready."

DEAR MISS MANNERS: My sister-in-law attended my mother's funeral visitation as one of the first to arrive and the last to leave (a 2 1/2-hour stay). She had met my mother only a few times and knew very few of the guests attending.

She managed to join in on every conversation, felt the need to inquire about who the guests were and why they were there, stated how hard the day was for her since it brought back memories of her own mother who died six years ago, and cried and hugged everyone in sight.

When she finally left along with the last guest, she stated, "How fun."

Is it wrong for me to be upset that she used my family's grief as her social outing for the week and her topic of conversation to anyone who is "stuck" listening to her for the next several weeks?

GENTLE READER: No, it is not wrong. But unfortunately, saying it is.

Miss Manners does not see any polite, or even reasonable, way to put it. "I am sorry, but your show of grief was excessive, given your limited relationship to my mother"? or "Please don't socialize at my mother's funeral"?

Controlling another's demonstrated grief, no matter how misplaced and excessive it might be, is a fruitless and unbecoming task. At the very least, think of your sister-in-law's antics as a momentary respite from your own more tempered and legitimate bereavement.

DEAR MISS MANNERS: My wife and I attended the wedding of a friend of hers. As we entered, an usher asked my wife, "Bride or groom?" then extended his arm, which she gladly accepted. He escorted her to the seat, never acknowledging my presence.

I told my wife I felt that was out of line. We entered as a couple, and why were you being led in another man's arm? She disagreed and said this is standard practice. I am a photographer who has done plenty of weddings, but I've never seen this done. I need you to settle this debate.

GENTLE READER: It is standard practice.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)