DEAR MISS MANNERS: At my company, we have our personal cellphone numbers on our business cards, which is fine. Nowadays it would seem like burying our heads in the sand to pretend that it’s impossible to reach us outside the office.

However, I think it should be an unwritten rule that business acquaintances should only use that number when there’s a time-sensitive issue and they can’t reach me at the office.

The vast majority of people who have my card do treat it that way. However, there are a few who simply call my cell number freely, for reasons that aren’t urgent. (For what it’s worth, I don’t work in medicine or any other field where reaching me is actually life-or-death.)

To me, it’s like giving a neighbor an emergency key to your house. You want them to have it in case there’s ever a need, but you don’t want them using it to drop in for a midnight snack.

Is there a polite way to let people know that for ordinary business, they should really only call me at the office? Or should I just accept that since I’ve given them my cellphone number, they get to use it?

GENTLE READER: How would they know any better?

With the lines blurred between business and social situations and their respective calling cards (social cards being virtually nonexistent -- or existent only virtually), callers have no choice but to use the number that they are offered.

Miss Manners recommends that you create new business cards with only your office phone number listed. Then, if you find yourself with clients who will need more direct access to you, you may invite them to use your mobile telephone number and scribble it in by hand.

A conspiratorial “I only do this for clients I trust with my personal information” can be added, if you can muster it up without sounding creepy.

DEAR MISS MANNERS: When friends or family cancel after accepting an invitation, who bears the burden of rescheduling?

A friend canceled plans for lunch at our home -- the morning of the lunch. A family we know canceled a long-planned day trip because an event that their child had to attend came up after they accepted our invitation. Last summer, my brother and his family, who live about two hours away, canceled a holiday-weekend visit to our home -- the day before we expected them -- because their pet-care plans fell through.

I completely understand that life happens, but none of these people suggested an alternative plan when they canceled, and none have reached out to reschedule since then.

I have always thought the burden of rescheduling lies with the canceling party, but since no one has done it, I question my judgment. I also question whether it’s worth reinviting them to new events; it’s fair to conclude that they are signaling a lack of interest in socializing with us, and I don’t want to put people in the position of scrambling to politely decline. How would you proceed at this point? Are there different standards for friends and family?

GENTLE READER: You may stop issuing invitations to ungracious friends. To family, you may only stop issuing them with enthusiasm.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: When someone has put forth the effort to surprise me with a present, I prefer to express my gratitude in a handwritten note. Sometimes, however, I receive a gift that has been shipped to me.

Is it out of place to send an email thank-you immediately so they know I have received their surprise? Such an email would, of course, be followed with the preferred handwritten correspondence.

GENTLE READER: What is your hurry?

Although she insists on prompt thank-you letters, Miss Manners does not understand the necessity for instantaneous ones. Assuming a reasonable response time, no sensible giver would quibble over the one or two days taken by the mail.

As she agrees that the letter of thanks, not the email, is the genuine article, she suspects that your concern -- which is shared by many of her Gentle Readers -- has been shaped by the corporate world. Watching on one’s computer as a package fitfully wends its way across the country, or on one’s cellphone as the car makes multiple wrong turns trying to find you, are now everyday occurrences.

Miss Manners is mystified why customers are content with documentation of incompetence in place of speedier delivery, but she notes that they are nevertheless conditioned to waiting.

DEAR MISS MANNERS: I have a co-worker who brought up a disgusting topic at lunch. I told her I had a very weak stomach and to please talk about something else. She continued her conversation, so I picked up my lunch and went to another room to eat.

Today she insisted on talking about “chicken poop” at the lunch table. She giggled when she realized it had ruined my lunch. She thinks it is cute. I think it is rude. Am I being too sensitive?

GENTLE READER: As your co-worker’s enjoyment of her own unseemly behavior only works with an audience, you are right to deprive her of one. Reasoning with her is clearly ineffective.

But Miss Manners suggests also depriving her of the pleasure of appearing to shock you, by picking up your food and leaving with merely a muted, resigned disappointment.

DEAR MISS MANNERS: My manager lost his mother this morning. In his email informing us of his bereavement (and the fact that he’ll be out of the office), he clearly mentioned, “No condolences necessary.”

What is the proper etiquette in this situation? Do I respect his wishes and act completely normal (which seems rude), or do I send him a personal note?

GENTLE READER: People in your manager’s situation are sometimes not entirely sure what they want. Miss Manners does not say this as a preface to suggesting you ignore his wishes, but rather as a warning that whatever you do is equally likely to offend.

He may well consider it rude of you to ignore the death of his mother; he may also take umbrage at flowers expressing your sadness at the news. The safest course is the middle one: Omit the usual handwritten note to his home (complying with his request), but respond to his email saying how sorry you are (thereby showing sympathy) and asking if there is anything you can take care of for him in the office during his absence.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I am a graduate student, renting a house (that I fully furnish). To help reduce my expenses, I sublet the other rooms to grad students like myself.

I have always told my housemates that I have no problem with occasional houseguests coming for a short period, provided they give prior notice and don’t overstay their welcome. For the most part, my housemates have been considerate, but this past weekend has me stumped.

One of them had a friend and her boyfriend come to stay for the weekend. When I entered the house and saw the couple, no one offered any formal introductions. The couple basically ignored me, even though I was in the same room they were all in.

The next morning, I was in the kitchen and one of the visitors came downstairs, started opening up the cupboards and proceeded to ask me where the glasses were. Again, no “good morning,” no introduction. Just, “Where are the glasses?” (Which are all mine, by the way.)

I am appalled. In the Caribbean, where I’m from, it is customary when you are visiting someone’s home to bring a small token of gratitude for all the residents of the house, e.g., a bottle of wine or such. You introduce yourself to all inhabitants you meet while in the home (or at the very least, you say “Good morning” if you see them), and you take your friends out to dinner to thank them for their hospitality.

I have noticed a trend with folks coming to stay and treating the house like a hotel and me like the staff. Has this always been the “norm”? I was really offended by this experience.

GENTLE READER: While she cannot condone the rudeness of ignoring a person standing (in this case, also sleeping) nearby, Miss Manners notes that your housemates are your tenants, and their guests are not your guests.

If you are a host, why are you charging rent? If you are a landlord, why do you expect gifts?

As the social pattern doesn’t work, you should try a professional approach. Written instructions about use of the facilities, either distributed or posted, may not be necessary. But asking your tenants to introduce you to their guests -- or introducing yourself if you meet them alone -- would be a start.

DEAR MISS MANNERS: I occasionally invite a friend or friends to join me at a restaurant in order to use a coupon. The coupon has an expiration date, so I mention this when issuing the invitation.

If my friend can’t go on the date I suggest, he or she will usually say, “I’ll let you know a date when I can go.” Time passes, the coupon is about to expire, so I begin to wonder whether it is better to prompt the friend or extend the invitation to someone else. What is the correct thing to do?

GENTLE READER: Although Miss Manners prohibits rescinding invitations, this is not applicable. Your initial invitation was rejected. You need only express sadness that that date did not work out, and agree that you would be happy to do some other, non-coupon activity on a more convenient date.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)