diff --git a/core/Dockerfile b/core/Dockerfile
index ca904e6..9b80900 100644
--- a/core/Dockerfile
+++ b/core/Dockerfile
@@ -9,6 +9,8 @@ RUN --mount=type=cache,target=/root/.cache \
     apk update \
     && apk add --virtual build-deps gcc python3-dev musl-dev postgresql-dev \
        libffi-dev \
+  # Mailman html to plaintext conversion uses lynx.
+    && apk add --no-cache lynx \
   # psutil needs linux-headers to compile on musl c library.
     && apk add --no-cache bash su-exec postgresql-client mysql-client curl python3 py3-pip linux-headers py-cryptography mariadb-connector-c \
     && python3 -m pip install -U pip setuptools wheel \