diff -Naur cyrus-imapd-2.2.2-BETA/imap/lmtpd.c cyrus-imapd-2.2.2-BETA-autosievefolder.uncompiled/imap/lmtpd.c
--- cyrus-imapd-2.2.2-BETA/imap/lmtpd.c	2003-10-24 21:24:06.000000000 +0300
+++ cyrus-imapd-2.2.2-BETA-autosievefolder.uncompiled/imap/lmtpd.c	2003-12-15 14:33:48.775254000 +0200
@@ -167,6 +167,8 @@
 static int sieve_usehomedir = 0;
 static const char *sieve_dir = NULL;
 #endif
+static int autosieve_subfolder(char *userid, struct auth_state *auth_state,
+                               char *subfolder); 
 
 /* per-user/session state */
 static struct protstream *deliver_out, *deliver_in;
@@ -623,6 +625,19 @@
                           sd->username, mdata->notifyheader,
                           fc->mailbox, quotaoverride, 0);
 
+    if (ret == IMAP_MAILBOX_NONEXISTENT) {
+	/* if "plus" folder under INBOX, then try to create it */
+	ret = autosieve_subfolder(sd->username, sd->authstate, fc->mailbox);
+	
+	if (!ret)
+	    ret = deliver_mailbox(md->data, mdata->stage, md->size,
+				  fc->imapflags->flag, fc->imapflags->nflags,
+				  sd->username, sd->authstate, md->id,
+				  sd->username, mdata->notifyheader,
+				  fc->mailbox, quotaoverride, 0);
+     }
+		
+
     if (ret == 0) {
 
 	snmp_increment(SIEVE_FILEINTO, 1);
@@ -1472,3 +1487,89 @@
     append_removestage(stage);
 }
 
+
+#define SEP '|'
+ 
+static int autosieve_subfolder(char *userid, struct auth_state *auth_state,
+                               char *subfolder) 
+{
+     char foldername [MAX_MAILBOX_NAME+1];
+     char f [MAX_MAILBOX_NAME+1];
+     const char *subf ;
+     char *p, *q, *next_subf, *mbox;
+     int len, r = 0;
+     int createsievefolder = 0;
+ 
+   
+    /* Check if subfolder is NULL */ 
+    if(subfolder == NULL) 
+       return IMAP_MAILBOX_NONEXISTENT; 
+ 
+    if ((subfolder[0] != 'i' && subfolder[0] != 'I') ||
+                  strncasecmp(subfolder, "inbox", 5) ||
+               subfolder[5] != lmtpd_namespace.hier_sep)
+        return IMAP_MAILBOX_NONEXISTENT;
+ 
+ 
+    if (config_getswitch(IMAPOPT_ANYSIEVEFOLDER))
+        createsievefolder = 1;
+    else if ((subf = config_getstring(IMAPOPT_AUTOSIEVEFOLDERS)) != NULL) {
+             /*
+              * mbox contains only the subfolder to be created name
+              */
+              mbox = strchr(subfolder, (int) lmtpd_namespace.hier_sep); 
+              mbox++;
+
+ 
+              /* Roll through subf */
+              next_subf = (char *) subf;
+              while (*next_subf) {
+                    for (p = next_subf ; isspace((int) *p) || *p == SEP ; p++);
+                    for (next_subf = p ; *next_subf && *next_subf != SEP ; next_subf++);
+                    for (q = next_subf ; q > p && (isspace((int) *q) || *q == SEP || !*q); q--);
+       
+                    if (!*p) continue;
+                    /*
+                     * This is a preliminary length check based on the assumption
+                     * that the *final* internal format will be something
+                     * like user.userid.subfolder(s).
+                     */
+		    len = q - p + 1;
+
+                    if (len  > sizeof(f) - strlen(userid) - 5)
+                        r = IMAP_MAILBOX_BADNAME;
+ 
+                    if (!r) {
+                        strncpy(f, p, len);
+                        f[len] = '\0';
+ 
+                        if (!strcmp(f, mbox)) {
+                            createsievefolder = 1;
+ 		            break;
+                        }
+                    }
+              }              
+         }
+ 
+    if (createsievefolder) {
+        /* Translate any separators in user */
+        if (userid) mboxname_hiersep_tointernal(&lmtpd_namespace, userid, 0);
+    
+        r = (*lmtpd_namespace.mboxname_tointernal) (&lmtpd_namespace,
+                                               subfolder, userid, foldername);
+        if (!r)
+            r = mboxlist_createmailbox(foldername, MAILBOX_FORMAT_NORMAL, NULL,
+                                           1, userid, auth_state, 0, 0, 0);
+        if (!r) {
+            mboxlist_changesub(foldername, userid, auth_state, 1, 1);
+            syslog(LOG_DEBUG, "Ondemand subfolder: User %s, subfolder %s creation succeeded.",
+                                                   userid, foldername);
+            return 0;
+        } else {
+            syslog(LOG_ERR, "Requested subfolder: User %s, subfolder %s creation failed. %s",
+                                                  userid, foldername,error_message(r));
+            return r;
+        }
+    } else 
+        return IMAP_MAILBOX_NONEXISTENT;
+}
diff -Naur cyrus-imapd-2.2.2-BETA/lib/imapoptions cyrus-imapd-2.2.2-BETA-autosievefolder.uncompiled/lib/imapoptions
--- cyrus-imapd-2.2.2-BETA/lib/imapoptions	2003-10-22 23:05:15.000000000 +0300
+++ cyrus-imapd-2.2.2-BETA-autosievefolder.uncompiled/lib/imapoptions	2003-12-15 14:33:49.492904000 +0200
@@ -544,6 +544,15 @@
 /* If enabled, lmtpd will look for Sieve scripts in user's home
    directories: ~user/.sieve. */
 
+{ "anysievefolder", 0, SWITCH }
+/* It must be "yes" in order to permit the autocreation of any INBOX subfolder 
+   requested by a sieve filter, through the "fileinto" action. (default = no) */
+
+{ "autosievefolders", NULL, STRING }
+/* It is a "|" separated list of subfolders of INBOX that will be automatically created, 
+   if requested by a sieve filter, through the "fileinto" action. (default = null)
+   i.e. autosievefolders: Junk | Spam */
+
 { "singleinstancestore", 1, SWITCH }
 /* If enabled, lmtpd and nntpd attempt to only write one copy of a message per
    partition and create hard links, resulting in a potentially large