比如你的导师、朋友或者师兄、师姐。杂志编辑邀请审稿的邮件 「Invitation to Review for xxx」，往往有类似这样的文字：
If you do not wish to review this paper, please click this link: xxxxxx. I would be very grateful for suggestions for alternative reviewers; however, please do not approach anyone directly, as the manuscript should be kept confidential.
If you are unable to review at this time, I would be grateful if you could recommend another expert reviewer.
包括主编和副主编。有些杂志的主编并不负责分配稿件，而是由手下的副主编、甚至专职编辑来完成。下面是我要推荐信的模板，因为考虑到编辑可能没有时间看附件，我并没有附上自己的简历，而是在邮件中一目了然地给出了自己的 Google Scholar 链接。发邮件的同时，记得在该杂志的网站上用同一个邮箱注册自己的信息。因为杂志编辑可能不会回复你的邮件，而是收到和你研究方向类似的稿件时，直接邀请你审稿。
My name is xxx, I’m a postdoc at xxx University. I am writing to get your recommendation so I can be selected as a reviewer for xxx journal. My research field are as follows: xxx.
I have published original research papers in several peer-reviewed journals such as xxx, xxx, and xxx. I have strong background, expertise and experiences in xxx. You can check my Google Scholar profile at: xxx.
I’m trying to further expand my knowledge and ability in the fields that your journal covers, and I would appreciate the opportunity to serve as a referee to review papers for you.
发邮件的时候要有的放矢，尽量给和你研究领域相近的编辑，因为编辑手里分配到的稿件往往和他们的研究领域接近，这样会增加你的审稿机会。把邮件发给 open access 的杂志可能会增加命中率，因为 open access 的杂志往往出版量大，审稿机会相对会多。
收到编辑发来的审稿邀请，要及时点击 「Agreed」 链接进行确认，会收到回复 「Thank you for agreeing to review for xxx」，这是递交绿卡申请需要的两封邮件之一。我们和亚洲以及欧洲有时差，很多时候收到邮件都是夜里，建议早晨起床或者到办公室后，第一时间检查邮件、并完成审稿确认。这些邀请可能同时发给多人，比如编辑给5个人发了邀请，但他其实只需要3个审稿人，说不定你还来不及回复、就已经收到编辑发来的取消审稿的邮件，因为已经有3个人确认了。
通过审稿可以第一时间了解到相关领域最新的科研进展，还可以通过这一学术活动建立自己在全球的科研学术网络，有益于建立未来的合作关系[参考]。仔细阅读审稿文章，从文章重要性（结果对该领域的重要性是什么？）和新颖性（文中的主张是否足够新颖、因此值得发表？研究是否在已有发表工作基础上取得进展？）这两个方面给出正面和反面的评价。网上提交审稿意见后，会收到确认审稿完成的感谢邮件 「Thank you for the review of xxx」，这是递交绿卡申请时需要的两封邮件之二。
Subject: Request for Supporting Letter for xxx’s Immigration Petition
Dear Dr. XXX,
My name is xxx, and I am currently working at xxx（工作单位）. I am writing this letter to inquire about the possibility of receiving a supporting letter from you toward my application of permanent residency in the United States of America.（发邮件的目的。）
My research has been focusing on xxx, xxx and xxx（一两句话概括自己的研究内容）. I read your great papers titled 「xxx,」 which was published on xxx journal in 2016, and 「xxx,」 which was published on xxx in 2016. They are very inspiring. It is also my honor to notice that you cited one of my papers 「xxx」, which was published when I was working in xxx’s group at xxx. I would like to express my appreciation for your great papers and also for your citation of my work.（我读过您发表的文章，受益匪浅；并且您的这些文章引用过我写的文章。我个人感觉这样一下子就把自己和推荐人的距离拉近了。）
As I have started my career here in the U.S., I plan to apply for the permanent residency under the 「Alien of Extraordinary Ability」 category, for which I need to submit evidence to the U.S. government of my qualification as an outstanding researcher. Such evidence includes a number of supporting letters signed by independent experts who do not know me personally and have never worked with me on any projects. Since you are a prominent figure in my research area, I wonder if you could help me out with such a letter, which will only be used for immigration purpose and will never be used as an academic recommendation. （进一步解释为什么需要推荐信让推荐人打消疑虑。）
I understand that you are extremely busy. Therefore, I have attached a well-written draft, along with my CV, for you to review and evaluate. You can modify in however you feel comfortable based on the draft, or you are more than welcome to write your own. I also understand that you may decline, and I will thank you for your time nevertheless. （考虑到推荐人可能太忙，进一步说明自己可以起草推荐信，供对方参考）
Thank you in advance for your help. I am looking forward to your reply!
至于推荐信的模板 draft，可以在未名论坛上找到很多。对你的评价中，「he may xxx」 之类的词语尽量不要出现。想想如果连推荐信都这么犹豫、不确定，怎么能让审查员信服呢？