diff -ruN netqmail-1.06-orig/chkuser.c netqmail-1.06/chkuser.c
--- netqmail-1.06-orig/chkuser.c	2019-08-05 19:11:16.583873852 +0200
+++ netqmail-1.06/chkuser.c	2021-06-19 12:54:40.238683686 +0200
@@ -276,6 +276,12 @@
 #if defined CHKUSER_ALLOW_SENDER_CHAR_10
                 && (user->s[x] != CHKUSER_ALLOW_SENDER_CHAR_10)
 #endif
+#if defined CHKUSER_ALLOW_SENDER_CHAR_11
+                && (user->s[x] != CHKUSER_ALLOW_SENDER_CHAR_11)
+#endif
+#if defined CHKUSER_ALLOW_SENDER_CHAR_12
+                && (user->s[x] != CHKUSER_ALLOW_SENDER_CHAR_12)
+#endif
 		&& (user->s[x] != '_') && (user->s[x] != '-') && (user->s[x] != '.') && (user->s[x] != '=')) {
                         return 0;
                 }
@@ -377,6 +383,12 @@
 #if defined CHKUSER_ALLOW_RCPT_CHAR_10
                 && (user->s[x] != CHKUSER_ALLOW_RCPT_CHAR_10)
 #endif
+#if defined CHKUSER_ALLOW_RCPT_CHAR_11
+                && (user->s[x] != CHKUSER_ALLOW_RCPT_CHAR_11)
+#endif
+#if defined CHKUSER_ALLOW_RCPT_CHAR_12
+                && (user->s[x] != CHKUSER_ALLOW_RCPT_CHAR_12)
+#endif
 		&& (user->s[x] != '_') && (user->s[x] != '-') && (user->s[x] != '.') && (user->s[x] != '=')) {
                         return 0;
                 }
diff -ruN netqmail-1.06-orig/chkuser_settings.h netqmail-1.06/chkuser_settings.h
--- netqmail-1.06-orig/chkuser_settings.h	2021-06-19 12:47:59.873380952 +0200
+++ netqmail-1.06/chkuser_settings.h	2021-06-19 12:53:57.838075220 +0200
@@ -424,17 +424,18 @@
  * Remember: '#' and '+' are accepted by CHKUSER_ALLOW_SENDER_SRS
  *
  */
-#define CHKUSER_ALLOW_SENDER_CHAR_1 "'"
-#define CHKUSER_ALLOW_SENDER_CHAR_2 '='
-/* #define CHKUSER_ALLOW_SENDER_CHAR_2 '%' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_3 '£' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_4 '?' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_5 '*' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_6 '^' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_7 '~' */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_8 '&' */	/* available for other characters */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_9 '#' */ 	/* available for other characters */
-/* #define CHKUSER_ALLOW_SENDER_CHAR_10 '=' */ 	/* available for other characters */
+#define CHKUSER_ALLOW_SENDER_CHAR_1 '$'
+#define CHKUSER_ALLOW_SENDER_CHAR_2 '%'
+#define CHKUSER_ALLOW_SENDER_CHAR_3 '£'
+#define CHKUSER_ALLOW_SENDER_CHAR_4 '?'
+#define CHKUSER_ALLOW_SENDER_CHAR_5 '*'
+#define CHKUSER_ALLOW_SENDER_CHAR_6 '^'
+#define CHKUSER_ALLOW_SENDER_CHAR_7 '~'
+#define CHKUSER_ALLOW_SENDER_CHAR_8 '&'	  /* available for other characters */
+#define CHKUSER_ALLOW_SENDER_CHAR_9 '#'   /* available for other characters */
+#define CHKUSER_ALLOW_SENDER_CHAR_10 '='  /* available for other characters */
+#define CHKUSER_ALLOW_SENDER_CHAR_11 '/'  /* available for other characters */
+#define CHKUSER_ALLOW_SENDER_CHAR_12 '\''  /* available for other characters */
 
 
 /*
@@ -446,16 +447,18 @@
  * Remember: '#' and '+' are accepted by CHKUSER_ALLOW_RCPT_SRS
  *
  */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_1 '$' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_2 '%' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_3 '£' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_4 '?' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_5 '*' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_6 '^' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_7 '~' */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_8 '&' */ 	/* available for other characters */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_9 '#' */ 	/* available for other characters */
-/* #define CHKUSER_ALLOW_RCPT_CHAR_10 '=' */ 	/* available for other characters */
+#define CHKUSER_ALLOW_RCPT_CHAR_1 '$'
+#define CHKUSER_ALLOW_RCPT_CHAR_2 '%'
+#define CHKUSER_ALLOW_RCPT_CHAR_3 '£'
+#define CHKUSER_ALLOW_RCPT_CHAR_4 '?'
+#define CHKUSER_ALLOW_RCPT_CHAR_5 '*'
+#define CHKUSER_ALLOW_RCPT_CHAR_6 '^'
+#define CHKUSER_ALLOW_RCPT_CHAR_7 '~'
+#define CHKUSER_ALLOW_RCPT_CHAR_8 '&'  	/* available for other characters */
+#define CHKUSER_ALLOW_RCPT_CHAR_9 '#' 	/* available for other characters */
+#define CHKUSER_ALLOW_RCPT_CHAR_10 '=' 	/* available for other characters */
+#define CHKUSER_ALLOW_RCPT_CHAR_11 '/'  /* available for other characters */
+#define CHKUSER_ALLOW_RCPT_CHAR_12 '\''  /* available for other characters */
 
 
 /*