In e-mail correspondence, the author of an competing paper has admitted a shortcoming of their method, roughly: "Yes, our method X does not work when used with Y." This is not obvious from their paper and is quite a big point from my perspective.

Can I cite this e-mail correspondence in my master thesis/paper (is there a difference?) and use as motivation for my work? Is this impolite? If I just say, X does not work with Y without citation, I feel reviewers will not believe me/say I did not apply the method accordingly.

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    I think you can find the relevant answers in the earlier thread academia.stackexchange.com/questions/43154/…
    – greenb
    Nov 8, 2016 at 12:36
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    While the answers address the point at hand, it's worth noting that Appeal to Authority is a fallacy and should be avoided wherever possible. It could well be that the authors of the method underestimate its capability or don't fully understand it. If there is a deficiency in the method when applied in certain cases it is probably far better that you either prove or demonstrate it is such rather than falling back on an opinion expressed in passing.
    – J...
    Nov 8, 2016 at 13:00
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    If your e-mail correspondence took place on a mailing list, chances are that there's a publicly available archive of all its discussions (including yours), which could be a slightly better source for citation since the reader can check it. (Probably not the case here, but who knows...)
    – hunger
    Nov 8, 2016 at 14:20
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    While this is not strictly relevant, it may provide some clarifying guidance. In the engineering world we reference email communications all the time and the typical procedure is to reference it as normal, and then attach it (the full email chain) to the document. This ensures that the information can be readily verified and seen in context by future readers. Particularly for peer-reviewed documents, the context contained in the full email chain is very important for proper verification.
    – wnnmaw
    Nov 8, 2016 at 17:05
  • Why don't you just ask for permission? Maybe include the sentence you plan to use; so that he gets a chance to improve the wording. There is a big difference between "does not work at all" and "does not work as good as we hoped". But as a reviewer I'd expect you to deliver an explanation why it foes not work, whether the original author agreed or not... Nov 8, 2016 at 20:30

3 Answers 3


The exact manner of how you should cite the communication may vary from style to style (often the date is included), but it's entirely reasonable to cite such a communication in a paper or thesis. Typically this is referred to as a Personal Communication. Obviously, wherever possible, you should look for information in published sources, but where this is not possible citing such a personal communication will suffice.

From memory, I think there might be one in my own thesis. A specific detail of an experimental method used in a published article was not discussed, but I thought it relevant to my argument so I contacted the author to get the information I needed.

Edit: Typically personal communications should not be included in the reference list as they are not evidence that can be readily recovered by anybody reading your work. This is made explicit in several prominent styles (e.g., Harvard, Chicago, APA).

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    So it is accepted in the research community, that e-mail communication is public and can always be cited? Interesting.
    – user64505
    Nov 8, 2016 at 12:34
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    @user64505 It is better to ask for permission.
    – user9482
    Nov 8, 2016 at 12:35
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    @user64505 You completely misunderstood the answer. Citing the email communication does not mean making it publicly avaiable! It simply means to write "[statement] as discussed in a personal communication between me and X" without putting any contents. In fact many countries have strict laws protecting the confidentiality of personal correspondence and email can be considered as such (e.g. in Italy). If you want to make the email text publicly available you have to request permission from the other recipients.
    – Bakuriu
    Nov 8, 2016 at 15:24
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    I did by no means intend to publicize the email. However, by citing, I make that fact, that the author him-/herself thinks that "X does not work with Y" public – a fact, which is not yet published.
    – user64505
    Nov 8, 2016 at 16:02
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    Still, you should ask for permission before citing a personal communication especially if there is some competition between you and the other correspondent. Regardless of legality, it is an important piece of courtesy.
    – PLL
    Nov 8, 2016 at 19:34

I would strongly advise against citing personal communications without express permissions (written or oral) of their authors.

As far as I understand, e-mail correspondence is deemed confidential "unless noted otherwise". For example, I often share my unpublished results with trustworthy colleagues . If they broke my trust, somebody could scoop the results.

Let me give you another reason. I believe people are much more casual in their e-mail than, say, in their journal articles, they do not check them as thoroughly, so they may be unhappy about their casual thoughts being published as their opinion without their permission. By asking their permission, you give them an opportunity "to think twice" about airing their views.

Maybe I should add an example. Some time ago a colleague disclosed my age in a forum. He had obtained the information from my e-mail. It is not that I hide my age, but neither do I publicly advertise it, so I had to reproach him for disclosing my personal information.


This is called personal communication and can be (and is occasionally) cited if no better references are available. There is nothing wrong with something like this (and it is certainly not impolite):

Method X (Smith et al., 2015) can very efficiently solve problem Z provided a number of prerequisites are fulfilled, but it cannot be applied with Y (Smith, personal communication, 2016).


Smith, Jones, Snyder (2015): The great method X, Nature, ...

Adjust to your citation style, which should have a template for personal communications.

Obviously, it would be better if you could elaborate on why it can't be applied with Y. Then you would not rely only on the personal communication.

Note that some journals ask for written permission from the person who is quoted [1]. It would also be polite to ask for this permission.

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    As an addition to the instruction to adjust to the citation style, it's also worth checking the style's rules are about references. I know, for example, that the APA style explicitly says to not include personal communications in the reference list, although it's okay to cite them.
    – Ian_Fin
    Nov 8, 2016 at 12:08
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    "some journals ask for written permission from the person who is quoted [1]." might be because in many countries doing this without such a consent is illegal...
    – Bakuriu
    Nov 8, 2016 at 15:26
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    @Bakuriu A literal quote from a personal email or letter might be illegal, but I doubt that saying "Dr. Smith told me the method doesn't work with Y." would be illegal anywhere.
    – user9482
    Nov 8, 2016 at 15:29
  • @Roland Depending on what Y is exactly, you may get in trouble either yourself or Dr. Smith. Imagine Dr. Smith signed an NDA about Y and told you something off the record. Nov 8, 2016 at 17:02
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    Let's not confuse legal issues with issues of trust and professional courtesy.
    – user9482
    Nov 8, 2016 at 17:05

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