add smtp service

smtp/Dockerfile

@@ -0,0 +1,13 @@
+FROM alpine:3.22
+
+WORKDIR /
+RUN apk add --no-cache git autoconf automake build-base gettext gettext-dev gnutls-dev libtool make texinfo
+RUN git clone https://github.com/marlam/msmtp.git --branch msmtp-1.8.32 --single-branch --depth 1
+WORKDIR /msmtp
+RUN autoreconf -fi && \
+  ./configure && \
+  make && \
+  make install
+ARG PORT=2500
+EXPOSE $PORT
+CMD ["msmtpd", "--port=$PORT"]