Mail Merging with letter.cls and envlab.sty
\documentclass{letter}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage[a4paper]{geometry}
\usepackage[british]{babel}
\usepackage{datatool}
\usepackage{graphicx}
\usepackage[nocapaddress]{envlab}
\DTLloaddb{people}{people.csv}
\DTLloaddb{countries}{country-codes.csv}
\SetBigLabel{101mm}{139mm}{9mm}{3mm}{2mm}{2}{2}
\renewcommand{\PrintBigLabel}[2]{%
\begin{minipage}[t][\LabelHeight]{\LabelWidth}%
\vfill
\hspace*{1em}%
\rotatebox[origin=l]{90}{\PrintReturnAddress{#1}}\hfill
\rule{0.1pt}{\ToAddressWidth}\space
\rotatebox[origin=l]{90}{\PrintAddress{#2}}%
\hspace*{1em}%
\vfill
\end{minipage}%
}
\makelabels
\name{Mr Big Head}
\signature{Big Head}
\location{Secret Lab of Experimental Stuff}
\address{University of Somewhere\\Some City\\AB3 4YZ}
\telephone{0123456789}
\begin{document}
\DTLforeach*{people}% data
{% assignments
\Id=id,%
\Surname=surname,%
\Forenames=forenames,%
\Title=title,%
\AddressI=address1,%
\AddressII=address2,%
\Town=town,%
\County=county,%
\Postcode=postcode,%
\CountryCode=country%
}
{%
\xDTLassignfirstmatch{countries}{code}{\CountryCode}{\CountryName=name}
\begin{letter}{\DTLifnullorempty{\Title}{}{\Title\ }%
\Forenames\ \Surname\\\AddressI\\
\DTLifnullorempty{\AddressII}{}{\AddressII\\}\Town\\
\DTLifnullorempty{\County}{}{\County\\}\Postcode\\\CountryName}
\opening{Dear \DTLifnullorempty{\Title}{\Forenames}{\Title} \Surname}
\thispagestyle{firstpage}
This is an imaginary letter.
This is the second paragraph of the letter.
\closing{Yours sincerely}
\ps PS: this is a postscript.
\encl{Photocopy of something interesting\\
Photocopy of something rather dull}
\cc{Prof Important Person\\Dr Bor Ing}
\end{letter}
}
\end{document}
Download mail-merging-letter-labels.tex or mail-merging-letter-labels.pdf.