\documentclass[stationery]{hduthesis}

\usepackage{lipsum}
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\DocInfo
  {
    title      = Recommendation Letter for SAN Chi Nan,
    author     = YIP Tsz Ching,
    mail       = email@server.domain,
    date       = {23\textsuperscript{th} December, 2024},
    watermark  = true
  }

\begin{document}

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Dear Prof. Wong,

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\vspace{\baselineskip} \raggedleft

Sincerely yours,\\[4ex]
\includegraphics[ height = 2em ]{hdutitle}\\[2ex]
Professor of Department of Physics\\
Room \meta{int}, Building \meta{int}, Hangzhou Dianzi University

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\end{document}