Configure fetchmail to use idfile to keep track of messages.

Run fetchmail as root. This is unfortunately required because
all files are owned by root in the mailu data folder.
In the future  we must switch all images to running all
all processes with a non-root user.

optional/fetchmail/Dockerfile

@@ -13,10 +13,7 @@ RUN apk add --no-cache fetchmail ca-certificates openssl \
  && pip3 install requests
 
 RUN mkdir -p /data
-RUN chown fetchmail:fetchmail /data
 
 COPY fetchmail.py /fetchmail.py
 
-USER fetchmail
-
 CMD ["/fetchmail.py"]

optional/fetchmail/fetchmail.py

@@ -13,7 +13,7 @@ import traceback
 
 FETCHMAIL = """
 fetchmail -N \
-    --idfile /data/.fetchids \
+    --idfile /data/.fetchids --uidl \
     --sslcertck --sslcertpath /etc/ssl/certs \
     -f {}
 """