I emailed to a professor about a research question. In most cases I reply to them asap. In some scenarios I think I cannot do this asap because:

  1. He asked me a very difficult question that takes a long time to get an answer.
  2. I don't have any further questions for now. But I might have them in the future.
  3. He does not show any interests on me. He's response is professional yet short (little interests). He does not ask me any questions. I don't have too much to say.

From what I read on this site, people seem to suggest that, since a professor reads thousands of emails, I should not bother to send another email unless it includes a considerable amount of new information.

However, my advisor told the contrary: to show respects, I should almost always send the last email: professors can ignore me but I cannot ignore them. For example, in case 1 I can say that "I will spend more time on this problem", in case 2&3 I can say that “Thank you for your answers. May I email you again if I have other questions later?". My advisor said something like: although everyone is equal, there is still a hidden "hierarchy" thing: lower people are expected to show more respects and do more works to maintain the relationships. I think he is trying to be honest here.

What is the standard etiquette in USA?

  • 2
    Might be a cultural thing, so I think this question would benefit from knowing your location.
    – Jeroen
    Oct 21, 2020 at 7:42
  • 1
    Your option "Thank you for your answers. May I email you again if I have other questions later?" is problematic, as you might get a "yes" or "no" in response, and would have to send another mail, thanking for his response..
    – Mark
    Oct 21, 2020 at 9:18
  • 2
    This might not be a good question for the Internet as chances are that the answers here tend to "People are all equal, there is no good reason that the prof may ignore you and you can't", "just change advisor if your advisor is unreasonable" etc because they are the ideal world answers. It might make more sense to talk to your real world friends, collegues and professors.
    – user111388
    Oct 21, 2020 at 10:46
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    You have done the right thing - you have asked your advisor for advice. Is there any reason you don't think his or her advice is good?
    – Sverre
    Oct 21, 2020 at 12:30
  • @Sverres Because the advice contradicts with the advice I got from this site
    – High GPA
    Oct 21, 2020 at 23:02

3 Answers 3


In the US, many professors really don’t like the idea that students tremble in fear at any interaction with them, and/or regard them as a class of semi-divine beings who need to be constantly flattered and paid homage to. Any idea that the student’s actions are motivated by ideas like

  • hierarchy

  • I should not bother to send another email unless it includes a considerable amount of new information

  • I should almost always send the last email

  • professors can ignore me but I cannot ignore them

  • lower people are expected to show more respects and do more works to maintain the relationships

  • Is it impolite to not to respond to professors' replying email asap?

  • etc

will be seen as upsetting and in many cases offensive to such professors.

The standard etiquette in the US is therefore to treat the professor with the same respect and professionalism that you yourself expect to be treated with (and that any professional person ought to expect to be treated with) by anyone in a professional working environment. That is, if the context of the email requires an urgent response, then you should answer with a corresponding urgency and immediacy; and if it doesn’t, then you should answer within a time frame that makes sense for that context. The fact that you are a student emailing a professor has no effect on whether the time interval to answer an email is polite or impolite.


The higher on the hierarchy people are, the less they will care about this.

The reason is simple: They don't even notice if you don't send an email.

If you had ever seen a professor's inbox, you'd understand just how many very important emails they receive. You can safely assume that they won't even remember that High GPA didn't send the last email in an exchange. You are lucky if they remember you at all (unless they know you personally).

Now, politeness is a very cultural concept. If your own culture and conscience requires sending a "thank you" email, by all means, send it. Usually, it will just be ignored, but there is a chance that someone will appreciate it.


I agree with Dan Romik's post above. The advice that your advisor shared does not, in my opinion, reflect US culture. As a professor, I am not offended or upset if a student does not reply to an email UNLESS I stated within the email that I needed a response. If a student does not send me a reply, I assume that my email addressed their concerns and that no further explanation is needed at the moment. Some of my students will reply with a brief 'thank you,' but this is not necessary.

  • I wonder if you will feel better if they send a short appreciation note at the end.
    – High GPA
    Jul 19, 2021 at 21:54

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