Dear Miss Manners: My sister-in-law seems unable to tolerate a reciprocal relationship where she accepts our hospitality or gift, and then she hosts us, gives us something, etc. If we visit her, she gives us gifts and insists on paying because we "came all that way," but if she visits us it's different. This time she needs to pay for things because we "did so much."

She argued that a coin flip would be unfair to determine which couple got the better room in a shared suite. (The only fair thing would be if she and hubby took the lesser accommodation.)

I thought we made headway in the last visit. They accepted our hosting, but also took us out. Now I just received, after the fact, an additional gift certificate by e-mail. I suffer from my own malady of really liking things to be equal, but this doesn't seem possible. What should I feel, do or say?

Gentle Reader: "Thank you," while trying not to sigh audibly. And when you take them out, make arrangements about the bill in advance.

In a world of moochers (such a satisfying word), excessive generosity may be a lesser annoyance, but Miss Manners thoroughly sympathizes with your discomfort.

However well your relatives think they mean, they are putting you in their perpetual debt, which is not pleasant.

You will, of course, thank them for the gift certificate. But you might want to add that you are saving it — whether it is a meal out, or a present you should choose — to enjoy with them on their next visit.

Punctuating thanks

Dear Miss Manners: I work in customer service, and every day I send 20 or so e-mails saying, "So-and-so, your order for X has been processed …"

Often my e-mails receive no response, but sometimes the recipient replies, "Thank you!" or "Thank you."

When he/she includes the exclamation point, I usually reply, "You're welcome!" so as to match the punctuation. However, I never know what to write when someone omits punctuation or uses a period.

"You're welcome" sounds kind of flat and could be seen as sarcastic or irritated.

Is it rude to refrain from responding? Should I nix the "You're welcome" for impersonal situations? I don't want to annoy people by blowing up their inbox with pointless pleasantries.

Gentle Reader: There are those who feel that "unnecessary" courtesies pose a mortal threat to cyberspace, but Miss Manners is not among them.

Recognizing that you are in customer service, Miss Manners would like to introduce you to the Reasonable Person — who does not read special meaning into a period at the end of a sentence. She trusts that a customer who takes time to write "Thank you" will not be incensed by your replying, "You are welcome" (thus settling the punctuation dilemma).

"Miss Manners" is Judith Martin of the Washington Post. Send questions to her website, missmanners.com.