scrletter change header and footer

Question

\documentclass{scrartcl}
\usepackage{scrletter}
\usepackage{scrlayer-scrpage}
\ofoot{A}
\pagestyle{scrheadings}
\clearpairofpagestyles
\chead{- \thepage\ -}
\begin{document}
\begin{letter}{}
page1
\newpage
page2
\end{letter}
\end{document}

The header and footer seems to have no effect. Probably because it is overwritten by scrletter? If I removed the letter environment, the defined pagestyle would be active

Answer 1

First of all: If the result should be a letter with a first letter page, you have to use \opening{...}! Then you will get a warning because of the empty mandantory argument in \begin{letter}{}. To avoid this warning use \begin{letter}[addrfield=false]{} if there is no recipient.

---

The second, third etc. page of the letter uses the page style saved in \letterpagestyle. By default this is plain.letter. You can redefine both styles plain.letter and letter by

\renewpairofpagestyles{letter}{%
  \clearpairofpagestyles%
  \ofoot*{A}
  \chead*{\pagemark}
}

Example:

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\usepackage{scrletter}% loads scrlayer-scrpage and sets page style scrheadings automatically
\renewpairofpagestyles{letter}{%
  \clearpairofpagestyles%
  \ofoot*{A}
  \chead*{\pagemark}
}
\renewcommand*\pagemark{\usekomafont{pagenumber}{- \thepage{} -}}
\let\letterpagemark\pagemark
\setkomavar{fromname}{Max Mustermann}
\begin{document}
\begin{letter}[addrfield=false]{}%<- option addrfield=false added, because there is no recipient given
\opening{Hello}% <- added!!
\Blindtext
\closing{Bye}
\end{letter}
\end{document}

Or you could redefine \letterpagestyle in the preamble to a page style of your choice. If \letterpagestyle is empty, then the page style of the document is used on these pages too.

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\usepackage{scrletter}% loads scrlayer-scrpage and sets page style scrheadings automatically
\clearpairofpagestyles
\ofoot{A}
\chead{\pagemark}
\renewcommand\pagemark{\usekomafont{pagenumber}{- \thepage{} -}}
\let\letterpagemark\pagemark
\renewcommand{\letterpagestyle}{scrheadings}% <- page style of the second, third etc. page of the letter
\setkomavar{fromname}{Max Mustermann}
\begin{document}
\begin{letter}[addrfield=false]{}%<- option addrfield=false added, because there is no recipient given
\opening{Hello}% <- added!!
\Blindtext
\closing{Bye}
\end{letter}
\end{document}

The result is the same as above.

---

The first letter page uses page style empty. If you want to use an other page style on the first letter page, you have to add \thispagestyle{...} next to \opening{...}. If this page style defines a page header, you have to add KOMA option firsthead=false to disable the default first page header.

Example:

\documentclass{scrartcl}
\usepackage{blindtext}% only for dummy text
\usepackage{scrletter}% loads scrlayer-scrpage and sets page style scrheadings automatically
\clearpairofpagestyles
\ofoot{A}
\chead{\pagemark}
\renewcommand\pagemark{\usekomafont{pagenumber}{- \thepage{} -}}
\let\letterpagemark\pagemark
\renewcommand{\letterpagestyle}{scrheadings}% <- page style of the second, third etc. page of the letter
\setkomavar{fromname}{Max Mustermann}
\begin{document}
\begin{letter}[
  addrfield=false,%<- option addrfield=false added, because there is no recipient given
  firsthead=false% <- disable the default header of the first letter page
]{}
\opening{Hello}% <- added!!
\thispagestyle{\letterpagestyle}%<- change page style of the first letter page
\Blindtext
\closing{Bye}
\end{letter}
\end{document}