\documentclass[12pt]{letter}

% ---------------------------------------------------------------
% Packages
% ---------------------------------------------------------------
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{microtype}
\usepackage[
  a4paper,
  top=3cm, bottom=3cm,
  left=3cm, right=3cm
]{geometry}
\usepackage{parskip}

% ---------------------------------------------------------------
% Sender information  ← fill these in
% ---------------------------------------------------------------
\address{
  Your Name \\
  Street Address \\
  City, Postcode
}

\signature{Your Name}

% ---------------------------------------------------------------
\begin{document}

\begin{letter}{%
  Recipient Name \\
  Street Address \\
  City, Postcode
}

% --- Opening -----------------------------------------------
\opening{Dear First Name,}

% --- Body ---------------------------------------------------
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Vivamus lacinia odio vitae vestibulum vestibulum.
Donec in efficitur leo, in commodo odio.

Curabitur pretium tincidunt lacus. Nulla gravida orci a odio.
Nullam varius, turpis molestie ultricies dapibus, tortor augue
rhoncus orci, eu porttitor neque eros nec erat.

Quisque erat eros, viverra eget pretium quis, tincidunt sed est.
Aliquam erat volutpat. Nam dui mi, tincidunt quis, accumsan
porttitor, facilisis luctus, metus.

% --- Closing ------------------------------------------------
\closing{Warm regards,}

\end{letter}
\end{document}