[Tex/LaTex] \address and \email. Undefined control sequence

Question

First I tried to find to find similar question but I have failed except in combine class(I don't know this class). This is my code

\documentclass{article}
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{graphicx}
\usepackage{setspace}
\newtheorem{theorem}{Theorem}
%\pdfoutput=1
\renewcommand{\baselinestretch}{1} 
\newtheorem{case}{Case}
\newtheorem{conclusion}{Conclusion}

\newtheorem{corollary}{Corollary}

\newtheorem{definition}{Definition}

\newtheorem{lemma}{Lemma}

\newtheorem{proposition}{Proposition}

\newenvironment{proof}[1][Proof]{\noindent\textbf{#1.} }{\ \rule{0.5em}{0.5em}}

\begin{document}

\title{XXX}

\author{XXX}
\address{AAAA}

\maketitle 

The file cntains "Undefined control sequence". Moreover I want to add my e-mail.
Thanks in advance.

Answer 1

You can do something like this

\documentclass{article}
\usepackage{authblk}
\usepackage{hyperref}
%
\newcommand*{\email}[1]{%
    \normalsize\href{mailto:#1}{#1}\par
    }
\title{Here is the title}
\author{An author}
\affil{This is some institute\\ \email{user@gmail.com}}

\begin{document}
\maketitle
\end{document}