documentclass{minimal}
usepackage[pdfusetitle]{hyperref}
usepackage{authblk}

%makeatletter
%hypersetup{pdfauthor={@author}}
%makeatother

begin{document}
title{The title}
author{Myself}

Content.

end{document}

title{The title}
author{Firstname Lastname}
author{Second author}
affil{First affiliation\
    href{mailto:firstname.fastname@affiliation}{firstname.fastname@affiliation}
}
author{Name3}
affil{Second affiliation}
makeatletter
    hypersetup{
        pdfauthor={Firstname Lastname, Second author, Name3}
    }
makeatother
maketitle