DEAR MISS MANNERS: I just received a sharp rebuke from a co-worker for sending him a personal email (following up on a prior conversation) at 5:45 in the morning. His reply stated only that "this exchange should not occur before 7 a.m."

I was taken aback by the tone of his reply. I have never exchanged emails with him outside of business hours before. Presumably, his smartphone alerts him of incoming email and my message disturbed his sleep.

I hadn't anticipated this -- I may be old-fashioned, but I still think of email as a desktop activity. Should I apologize for this apparent intrusion?

GENTLE READER: It used to be that surprise, late-night house calls were understood to be limited to those who could expect to be welcomed with open arms. Exceptions were made for emergencies, warrants and comic figures in Shakespeare plays.

But nocturnal knocks on the door and emails are not the same thing. You did not expect your co-worker instantly to act upon -- or even to see -- the early-morning email, any more than you would have expected an immediate response to a posted letter.

That the mail came early and set the dog barking, which in turn woke up the baby, who toddled down the stairs to the kitchen, terrifying grandma, who spilled her coffee, is not your responsibility.

That said, the best answer to your co-worker is to apologize and gently say that you were having the same problem until you discovered that it was possible to mute the sound announcing new emails on your phone.

DEAR MISS MANNERS: Is it necessary to bring the hostess of a potluck family dinner a hostess gift? Or is my contribution (as per her request), which is often more food than the hostess herself prepares, a hostess gift enough?

GENTLE READER: Hostess? What hostess?

Miss Manners has trouble thinking of someone who orders catered food from you as a hostess. And while you should not expect to be tipped if you also partook of these meals, the optional courtesy of another contribution is unnecessary.

DEAR MISS MANNERS: Due to health problems such as migraines, I am sometimes forced to cancel doctor appointments at the last minute.

When this happens, should I give a brief apology over the phone, send a written apology, or assume that the health professionals go on with their day relatively unaffected by my absence?

GENTLE READER: While it is reasonable to assume that doctors are familiar with -- and perhaps even sympathetic to -- the effects of illness, Miss Manners can assure you that they do not go on with the day unaffected by your absence.

They have been hit hard by the growing societal disregard for the commitment implicit in scheduling an appointment. Most medical offices now call beforehand to remind patients to show up. And an increasing number are registering their displeasure with absenteeism by charging fees for last-minute cancellations.

You do not want to be confused with patients who offer an invented illness to cover a less defensible reason ("I really don't feel like traipsing all the way downtown today"). A handwritten note of apology will reassure your doctor that you value her time. She is the last person you want suspecting you of feigning illness.

(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: My husband and I disagree on the subject of what constitutes a house guest overstepping the line when it comes to laundry. His family comes to visit us once a year -- usually for one week -- and he feels it's OK for them to have unlimited laundry privileges.

They will want to do a load about every other day, and always right before leaving, which makes me feel taken advantage of. For the time span of their visit, I feel like one load is plenty -- two would be the max if there was an unexpected problem. Please let us know what is appropriate.

GENTLE READER: You really dislike your in-laws, don't you?

As Miss Manners understands it, they visit once a year for a week, so laundry every second day would be four times a year -- at most. Apparently they do not ask you to do it, but only to use your washing machine.

Small acts of sabotage are unlikely to curb these visits. These are your husband's relatives, and he disapproves of your ploy. It will only make you look petty and inhospitable, to him as well as to them.

DEAR MISS MANNERS: I am a senior citizen who is quite often unseated on public transportation by someone younger and fitter than I am. Yesterday, after I had taken the last seat, I noticed that someone even older and less fit than I was being outraced by a man in his early 20s. I stood up and gave the loser of the race my seat.

So far, so good, as far as my behavior was concerned.

Now the evil part: I was really tempted to say to the young man who had won the race, "If you're disabled, please keep your seat," or "If you're disabled, don't get up. I'll give her my seat."

Later, as I sat there watching him in his oblivion, I wanted to whip out my camera and ask, "Do you mind if I take a picture of you sitting beneath the sign saying, 'The law requires you to make seats available to seniors and persons with disabilities'?"

Once, when I was really tired and traveling with someone 10 years older than I am, I actually told a young couple, "Thanks for saving these seats for us. You can get up now." (They did.)

What can I do to keep myself from behaving in a way that Miss Manners would not approve -- or a way that will get me shot?

GENTLE READER: If you are shot, you may take comfort in knowing that the shooter was behaving worse than you. If, however, you decided that the behavior of others justifies your retaliating in kind, you would be no better.

Worse, Miss Manners would say, because you would be pretending to be correcting the very behavior you are practicing.

But you didn't. You squelched your impulses to be rude and came up with a way of allowing the couple to vacate their seats without being embarrassed. Congratulations.

(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.)

(The formal announcement of the change will be made on Tuesday, Sept. 3; you can find our press release that day at universaluclick.com. Both Nicholas and Jacobina have co-written books with their mother, and now their collaboration will extend to newspapers. We are delighted to welcome Nicholas and Jacobina to Universal Uclick, and we know your readers will enjoy this new generation's take on manners in an ever-changing social world.)

DEAR MISS MANNERS: I joined Facebook when I had cancer, as a way of posting my current status. I was following others' suggestions and did not like it for this use. I do, however, like it for other reasons. I can keep an eye on my daughter, as well as my nieces and nephews.

I can also reconnect with old friends and, as a nostalgic person, I enjoy this. I also enjoy the ability to share photographs of said friends. I befriend only people I have fond memories of, or whom I just liked.

But that doesn't necessarily mean I actually want to resume an old friendship! As a mother of young kids who works part time and volunteers, I have a hard enough time finding time for my friends and myself as it is.

Now an old friend in a nearby town has befriended me. While I enjoyed her company in my 20s, the friendship ended when I realized how badly she was an alcoholic. Still, there were things I really enjoyed about her.

Now, 15 years later, she mentioned on Facebook that she would like to get together. I don't know if alcohol is still a problem, but I just can't extend myself that far, both in terms of where she lives and the potential for toxicity.

Can you think of a polite way to tell her (or others in similar situations) that I really enjoyed hearing from her and seeing her occasional posts, her family, etc., but that I don't particularly want to reconnect with her in person? Am I kidding myself about the possibility of a polite way to convey such a message?

GENTLE READER: No, there is no polite way to tell someone that you want to know their personal business but don't actually want to talk to them. This phenomenon used to be known as gossip, and in Miss Manners' opinion, Facebook has ruined its fun for everyone.

When you want to avoid human contact, the usual social rules apply. Tell her that this is an extremely busy time for you, but that you hope to connect in the (unspecified) future. To make it more convincing, for goodness' sake don't post your social life on Facebook for awhile.

DEAR MISS MANNERS: Is it rude to want to shake someone's hand while they are eating?

GENTLE READER: It's messy.

Miss Manners fails to see why it would be necessary. If the two are eating together, it's a bit late to shake hands, and if one person has just come upon the other, say at a restaurant, the greeting should be fleeting enough not to require the diner to swivel or stand in order to reach out a hand.

DEAR MISS MANNERS: One of my friends couldn't make it to my baby shower, so she had her gift sent to me after I said that I gave birth to a little boy. How do I properly word a thank-you note to someone for a gift that was very clearly for a little girl?

GENTLE READER: "George loves the pink tutu and can't wait to start taking ballet classes."

On the off chance that it was indeed intentional, Miss Manners is hoping to spare you a lecture on early gender identification.

(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.)