diff --git a/target/bin/listmailuser b/target/bin/listmailuser
index 83343c3a..95dbc070 100755
--- a/target/bin/listmailuser
+++ b/target/bin/listmailuser
@@ -47,6 +47,7 @@ do
   else
     echo
   fi
-done < "${DATABASE}"
+done < <(_filter_to_valid_lines "${DATABASE}")
+
 
 exit 0
diff --git a/target/scripts/helpers/utils.sh b/target/scripts/helpers/utils.sh
index f217b8d8..13d39d12 100644
--- a/target/scripts/helpers/utils.sh
+++ b/target/scripts/helpers/utils.sh
@@ -5,8 +5,16 @@ function _escape
   echo "${1//./\\.}"
 }
 
-# Check if string input is an empty line, only whitespaces
-# or `#` as the first non-whitespace character.
+# Returns input after filtering out lines that are:
+# empty, white-space, comments (`#` as the first non-whitespace character)
+function _filter_to_valid_lines
+{
+  grep --extended-regexp --invert-match "^\s*$|^\s*#" "${1}" || true
+}
+
+# TODO: Only used by `relay.sh`, will be removed in future.
+# Similar to _filter_to_valid_lines, but only returns a status code
+# to indicate invalid line(s):
 function _is_comment
 {
   grep -q -E "^\s*$|^\s*#" <<< "${1}"