diff --git a/conf/dovecot/dovecot.conf b/conf/dovecot/dovecot.conf
index e614c3796..e4ada80ab 100644
--- a/conf/dovecot/dovecot.conf
+++ b/conf/dovecot/dovecot.conf
@@ -38,16 +38,28 @@ ssl_prefer_server_ciphers = no
 ###############################################################################
 
 
+# Regular Yunohost accounts
 passdb {
   args = /etc/dovecot/dovecot-ldap.conf
   driver = ldap
 }
 
+# Internally, allow authentication from system user
+# who might want to send emails (e.g. from apps)
+passdb {
+  override_fields = allow_nets=127.0.0.1/32,::1/64
+  driver = pam
+}
+
 userdb {
   args = /etc/dovecot/dovecot-ldap.conf
   driver = ldap
 }
 
+userdb {
+  driver = passwd
+}
+
 protocol imap {
   imap_client_workarounds =
   mail_plugins = $mail_plugins imap_quota antispam
diff --git a/conf/postfix/main.cf b/conf/postfix/main.cf
index 19b40aefb..4d02fc5c0 100644
--- a/conf/postfix/main.cf
+++ b/conf/postfix/main.cf
@@ -107,7 +107,10 @@ virtual_alias_domains =
 virtual_minimum_uid = 100
 virtual_uid_maps = static:vmail
 virtual_gid_maps = static:mail
-smtpd_sender_login_maps= ldap:/etc/postfix/ldap-accounts.cf
+smtpd_sender_login_maps=
+   ldap:/etc/postfix/ldap-accounts.cf, # Regular Yunohost accounts
+   hash:/etc/postfix/sender_login_maps # Extra maps for system users who need to send emails
+
 
 # Dovecot LDA
 virtual_transport = dovecot