config: remove `chroot` for Dovecot & PostSRSd (#3208)

* remove PostSRSd chroot
* remove chroot for Dovecot

A dedicated file for Dovecot's chroot environments is easier to handle
and adjust later.

target/dovecot/10-master.conf

@@ -114,3 +114,5 @@ service dict {
     #group =
   }
 }
+
+!include chroot.inc

target/dovecot/chroot.inc

@@ -0,0 +1,47 @@
+# This file removes `chroot` environments that
+#
+# 1. are not strictly needed
+# 2. can cause problems
+#
+# See https://github.com/docker-mailserver/docker-mailserver/pull/3208#pullrequestreview-1366106516
+# and it's related PRs.
+
+service aggregator {
+  chroot =
+}
+
+service anvil {
+  chroot =
+}
+
+service director {
+  chroot =
+}
+
+service ipc {
+  chroot =
+}
+
+service old-stats {
+  chroot =
+}
+
+service imap-login {
+  chroot =
+}
+
+service managesieve-login {
+  chroot =
+}
+
+service pop3-login {
+  chroot =
+}
+
+service submission-login {
+  chroot =
+}
+
+service imap-urlauth-login {
+  chroot =
+}

target/postsrsd/postsrsd

@@ -36,6 +36,3 @@ SRS_REVERSE_PORT=10002
 # This is highly recommended as postsrsd handles untrusted input.
 #
 RUN_AS=postsrsd
-
-# Jail daemon in chroot environment
-CHROOT=/var/lib/postsrsd