A patch to fix the following issues (tx Ali Erturk TURKER):
more info here: https://notes.sagredo.eu/en/qmail-notes-185/installing-and-configuring-vpopmail-81.html#comment2814

1- vdelivermail.c checks spamassassin permissions, instead of maildrop permissions.

2- vopen_smtp_relay() return values corrected, so that open_smtp_relay() can detect and report database connection errors (vmysql.c, voracle.pc, vpgsql.c )

3- vdel_limits() core-dumps if a database connection is not available beforehand. (vmysql.c, voracle.pc )

diff -ruN vpopmail-5.4.33-original/vdelivermail.c vpopmail-5.4.33/vdelivermail.c
--- vpopmail-5.4.33-original/vdelivermail.c	2011-02-28 19:00:45.000000000 +0200
+++ vpopmail-5.4.33/vdelivermail.c	2023-02-17 14:10:02.573403715 +0300
@@ -644,7 +644,7 @@
          parse_email(maildir_to_email(address), TheUser, TheDomain, AUTH_SIZE);
          vpw=vauth_getpw(TheUser, TheDomain);
        }
-       if ( vpw!=NULL && (limits.disable_spamassassin==1 ||
+       if ( vpw!=NULL && (limits.disable_maildrop==1 ||
            (vpw->pw_gid & NO_MAILDROP)) ) {
 #endif
         if ( strncmp(quota, "NOQUOTA", 2) != 0 ) {
diff -ruN vpopmail-5.4.33-original/vmysql.c vpopmail-5.4.33/vmysql.c
--- vpopmail-5.4.33-original/vmysql.c	2023-02-17 14:09:09.872130173 +0300
+++ vpopmail-5.4.33/vmysql.c	2023-02-17 14:24:01.305747105 +0300
@@ -913,8 +913,8 @@
     if ( ipaddr == NULL ) {
         return 0;
     }
-
-    if ( (err=vauth_open_update()) != 0 ) return 0;
+    // open_smtp_relay() expects "-1" on database errors. "0" means duplicate record. (See vpopmail.c)
+    if ( (err=vauth_open_update()) != 0 ) return (-1);
 
     qnprintf( SqlBufUpdate, SQL_BUF_SIZE,
 "replace into relay ( ip_addr, timestamp ) values ( '%s', %d )",
@@ -1863,6 +1863,11 @@
 /************************************************************************/
 int vdel_limits(const char *domain)
 {
+ int err;
+
+    // CHECKS IF A DATABASE CONNECTION IS AVAILABLE, CONNECTS IF NOT.
+    // THIS CHECK PREVENTS "CORE-DUMP" OF vqadmin.cgi.
+    if ( (err=vauth_open_update()) != 0 ) return (err);
     qnprintf(SqlBufUpdate, SQL_BUF_SIZE, "DELETE FROM limits WHERE domain = '%s'", domain);
 
     if (mysql_query(&mysql_update,SqlBufUpdate))
diff -ruN vpopmail-5.4.33-original/voracle.pc vpopmail-5.4.33/voracle.pc
--- vpopmail-5.4.33-original/voracle.pc	2011-02-28 19:00:45.000000000 +0200
+++ vpopmail-5.4.33/voracle.pc	2023-02-17 14:18:27.347078902 +0300
@@ -779,7 +779,8 @@
         ++ipaddr;
     }
 
-    if ( (err=vauth_open_update()) != 0 ) return;
+    // open_smtp_relay() expects "-1" on database errors. "0" means duplicate record. (See vpopmail.c)
+    if ( (err=vauth_open_update()) != 0 ) return (-1);
 
     qnprintf( SqlBufUpdate, SQL_BUF_SIZE,
 "insert into relay ( ip_addr, timestamp ) values ( '%s', %d )",
@@ -1442,6 +1443,11 @@
 
 int vdel_limits( char *domain )
 {
+    int err;
+
+    // CHECKS IF A DATABASE CONNECTION IS AVAILABLE, CONNECTS IF NOT.
+    // THIS CHECK PREVENTS "CORE-DUMP" OF vqadmin.cgi.
+    if ( (err=vauth_open_update()) != 0 ) return(err);
     qnprintf( SqlBufUpdate, SQL_BUF_SIZE, "DELETE FROM limits WHERE domain = '%s'",
         domain);
     EXEC SQL PREPARE S FROM :SqlBufUpdate;
diff -ruN vpopmail-5.4.33-original/vpgsql.c vpopmail-5.4.33/vpgsql.c
--- vpopmail-5.4.33-original/vpgsql.c	2023-02-17 14:09:09.872130173 +0300
+++ vpopmail-5.4.33/vpgsql.c	2023-02-17 14:14:40.686873149 +0300
@@ -772,7 +772,8 @@
   time_t delete_time;
   int err;
     
-  if ( (err=vauth_open(1)) != 0 ) return;
+  // open_smtp_relay() expects "-1" on database errors. "0" means duplicate record. (See vpopmail.c)
+  if ( (err=vauth_open(1)) != 0 ) return (-1);
   delete_time = mytime - clear_minutes;
 
   snprintf( SqlBufUpdate, SQL_BUF_SIZE,