I am now applying for postdoc (mathematics) and starting to search for jobs in mathjobs. In quite a lot of situation, the job description ask for three letter of recommendation. My question are:

  • When they ask for three letter, for example here, can I have 4 or 5 letters sent to that university? (I planned to have 3-4 letter for research and 1 for teaching).

  • If I can only send three letter, is it preferable to have 3 letters all focusing on research aspects, or 2 on research and 1 on teaching (assuming that that postdoc job requires one to teach)?

  • 1
    The wording of that Stanford ad suggests the teaching letter doesn't count toward the three, since they ask for "preferably a teaching letter; and three letters of reference."
    – user37208
    Oct 3, 2016 at 22:13
  • Thanks. But for that example, can I provide four research letters? My advisor told me that it is quite common... @user37208 Oct 3, 2016 at 22:19
  • Absolutely. Unless they explicitly say to only submit three research letters, submitting four is fine.
    – user37208
    Oct 4, 2016 at 0:38

3 Answers 3


When a job posting asks for X research letters plus Y teaching letters, mathjobs still allows you to submit more than X + Y letters. (If mathjobs has an upper bound on the number of letters you can submit, I don't know it. I have seen files with at least ten letters, even though we ask for 3 + 1.)

In general, I think it is almost certainly okay to submit either the number of letters asked for or one more than that. For each additional letter that you want to submit, I would advise you to think about why you are doing it. Here are some things to remember:

  • It is not guaranteed that the hiring committee will read your entire application. If you submit, say, twice as many letters as asked for, there is a good chance that some of them will be read only very cursorily. This may not be what you want, since:

  • Virtually all letters I have ever read are "positive," i.e., they say good things about the candidate. But the impression created by sending Z letters is not the sum of the Z impressions created by sending each of the letters. Rather, unless each letter writer has qualitatively different very strong things to say about you, the total impression is some kind of weighted average of the letters, with the worst letters getting a higher weight than the best letters. Thus I think that for all but the most senior candidates it is probably a bad idea to submit more than four research letters: any more than that and it is very likely that the average impression would be raised by removing one of the letters. (Of course you still have the task of figuring out which are your best letters. But you should try to figure that out, not just admit defeat and submit way too many of them.)

In your case, it sounds like that they really are asking for 3+1 letters, and you want to send 4+1. That should be fine...but now is not too soon to try to figure out which of those four letters are the strongest and which are the weakest.

  • 1
    "I would advise you to think about why you are doing it" is almost as good as general advice for questions on this site as "What does your advisor say?" Oct 4, 2016 at 13:33
  • "But the impression created by sending Z letters is the sum" -- should there be a "not" somewhere in there?
    – Yemon Choi
    Oct 4, 2016 at 18:40

It is very usual for mathjobs postings to ask for 3 letters, including one for teaching. It is very usual for math postdoc applicants to submit 3-4 research letters and 1 teaching letter, even for such postings. You will have no problem doing so through mathjobs.


You can send more than 3 letters, put you might strategically choose to put letters that are the most enthusiasts and that boasts you the best, because usually an employer keeps in mind and focuses on what he see's first of a candidate). I assume and I strongly suggest you to have letters focused on both points (research and teaching). This ensures to show all your qualifications (it is a lot more specific), so its is more objective as well as more faithful to your real portray.

2 of my relatives were in a similar situation to yours (a master and a post doc). I hope you will get the position you seek for. Good luck.

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