DEAR MISS MANNERS: Occasionally a relative or acquaintance forwards blog posts or other web postings that I consider to be offensive.

When people say things of that sort in person, I always respond because I believe that silence indicates acquiescence. But forwarded messages seem different, and I think the wisest course is to ignore them.

Nonetheless, I don't want the people who send them to think that I welcome these or share their views. Is there a better response than silence?

GENTLE READER: Silence may still be taken as acquiescence. But there are an unlimited number of things that one can be offended by, and too little societal agreement on the severity of different offenses.

Taking offense therefore requires the two qualities that the offender is being accused of lacking: judgment and tact. According to Miss Manners, the important differences between the forwarded blog post and the unfortunate remark made at dinner are, first, the possibility that the sender may not mean to endorse everything being forwarded, and second, the ability to respond to the sender without involving the other recipients.

If the offense is severe enough to merit -- or require -- a response, it is still possible to communicate only with the sender. And it is both more polite and more effective if you can phrase your response so as to allow the original sender the possibility that he did not mean to endorse something hateful.

DEAR MISS MANNERS: We have dinner guests about two times a month. What should I say when one or more of my guests gets up and begins to clear the dishes while I am not even half finished with my dinner?

Surely that person is trying to help, and I do not want to embarrass or admonish my guest. "Please be seated until everyone is finished with their dinner" just does not sound right. Does Miss Manners have a solution?

GENTLE READER: She does -- in fact, she has several. First, ask your guest please not to trouble herself; you will take care of that. The words suggest that you are being gracious, but the tone must be serious enough to ensure you are taken seriously.

When your would-be helper pauses to consider, turn to another guest who is still eating and apologize: "I'm so sorry. I didn't notice you were still eating." This should settle any dispute. But if it does not, offer seconds.

DEAR MISS MANNERS: What is your opinion on the appropriateness of cruise ship guests who continue to wear formal wear to the main dining room when the cruise line's dress code only requires designer jeans and button-down shirts for men? I think ladies in long gowns in such circumstances to be similar to guests wearing white dresses to weddings!

GENTLE READER: How so? The rationale for wedding guests not wearing white is that they might be mistaken for the bride, or, less charitably, that they might outshine her.

Miss Manners doubts that passengers pack evening clothes with the hope of making other passengers look shabby. Rather, they are channeling the glamorous old days of ships, when evening clothes were the rule. Nowadays, there are few opportunities to dress up.

So let them enjoy it. If you feel outdone, you may bring dressy clothes of your own.

(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: Is there any way politely to turn down what I call a "trap" invitation like this?

"We would love for you to come for lunch (dinner, etc.) with us. Let us know which of the following dates you are free: (e.g.) the 12th, 13th, 15th, 16th, 17th, 24th, 25th."

To decline, the recipient is forced to lie or sound rude.

GENTLE READER: To lie or to be rude -- you are not alone in believing that such is the only choice when you are asked to do something you do not want to do.

Sadly, people who reject both of these responses are left believing that the only alternative is to cave to others' wishes.

The problem is with the rigid definition of lying. Outside of courtrooms, the standard of "the truth, the whole truth, and nothing but the truth" is not necessary. It is possible to decline an invitation graciously without giving any excuse ("Oh, I would have loved to, but I'm afraid I can't") or one that is so vague as to be meaningless ("You are so kind to ask, but unfortunately we are busy then").

Pedants may argue that these are lies: You would not really have loved to comply, and you are not actually all that busy. They fail to understand that these are conventional phrases, not meant to be taken literally. It is as if you would be condemned for saying "Good morning" when it is raining.

Usually, repeating these statements at each offer eventually makes the asker give up. But as you have noted, some people persist. In that case, you must expand the reply into a blanket excuse: "I'm so sorry, but this is a rather busy time for me. Thank you for thinking of me, though."

DEAR MISS MANNERS: I am an adult woman and have a professional career. I am extremely small-chested. Wearing a bra does not provide me with "support," nor is support needed.

I wear one anyway, because my mother taught me that it is indecent for a woman to go without. Even underneath demure clothing, it can be possible for others to see that the outline of straps is not present, or worse, notice that perhaps a woman is cold. According to Mom, this would lead observers to determine that the woman was of poor moral character.

When I explained to my husband that this is the only reason I bother to wear brassieres, he laughed and said that my mother was wrong. He does not believe it would be a breach of social norms to forgo a bra that is there only to prove its own existence (provided that my dress or top is not sheer or too tight).

I would love for him to be right, but I am not convinced he is the expert he thinks he is on this subject. Can you please provide guidance?

GENTLE READER: Interfering between a husband and wife on the subject of the lady's underclothes is not in Miss Manners' job description. She would rather attack those people who stare at a demure bodice closely enough to see what is underneath, and blatantly enough to make the wearer realize that they are doing so.

But in the interest of marital peace, she will whisper: So wear an undershirt.

(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've started getting text messages from acquaintances, co-workers and even clients that say, "Call me please." This isn't because I am unavailable, or that they have tried calling but I haven't answered; they simply want to talk to me about something. Perhaps it's just me, but I find this irritating.

If they want to talk to me, they should call me, and if I'm not available, they can leave a message and I will happily call them back. Am I wrong to be turned off by this relatively benign demand?

GENTLE READER: No. Miss Manners concurs. At best, this request is, as you noted, redundant. At worst, insulting, as it assumes that you are not familiar with the primary function of a cellular telephone.

This particular message also has the added annoyance of making it sound as if there is an emergency where there is none. Miss Manners recommends that next time this happens, you text back, "Oh no! Is my phone not working?" or "OK, I will" and take your time in doing so. This might confuse them, but will certainly amuse you. And may just also drive home your point.

DEAR MISS MANNERS: My son's mother-in-law has started signing and addressing herself as his mom with her last name initial. I am his mother, and I feel this is inappropriate.

GENTLE READER: Then stop reading his mail.

DEAR MISS MANNERS: My future loving spouse and I have limited our wedding invitations. In fact, my own mother was declined in her request to extend invitations to 15 relatives.

However, a close co-worker to my spouse has requested that he bring a third person. This would be an easy request to decline, except for his polygamous lifestyle. He has a legal spouse and a concubine in what he calls an open marriage.

We are accepting of alternative lifestyles, and understand the difficulty of having to select between wife and concubine. We feel it would be politically incorrect to not accept the third family member.

But it will be hard to explain to my mother why she could not extend invitations for family members while being able to (in her view) "allow a cheating adulterous man to witness our sacred marriage vows."

GENTLE READER: Never mind that you are eschewing relatives in favor of co-workers. Miss Manners has stated repeatedly that relatives should always take precedence over work relationships, and that mothers should certainly be allowed to reasonably invite theirs.

But you did say that this gentleman was close. Unfortunately (for your mother, mostly), as you surmised, it is a dangerous precedent to set that you can dictate the terms of a spousal relationship. (Although it seems to Miss Manners that since this man has already publicly declared that one of these women is his legal wife and one his concubine, he has already made that distinction himself.)

But if this man is indeed close, perhaps you can explain the problem and say that the guest list is already so limited that even your mother has had to make hard choices.

(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.)