diff --git a/TODO b/TODO
index b074e22..f8c6d73 100644
--- a/TODO
+++ b/TODO
@@ -37,8 +37,6 @@ Patterns.
   function being missing so far
 - this is needed for move detection, which would work only within one Channel
 
-normalize INBOX capitalization received from IMAP, to avoid anomalies.
-
 kill the concept of an INBOX, it is a relic from single-channel operation.
 if somebody needs it, he can have two stores with different Paths. the path
 can name a single (in-)box (curr. broken with maildir). an empty box name
diff --git a/src/drv_imap.c b/src/drv_imap.c
index dd0215f..4ea86d6 100644
--- a/src/drv_imap.c
+++ b/src/drv_imap.c
@@ -1232,8 +1232,20 @@ parse_list_rsp_p1( imap_store_t *ctx, list_t *list, char *cmd ATTR_UNUSED )
 	return parse_list( ctx, cmd, parse_list_rsp_p2 );
 }
 
+// Use this to check whether a full path refers to the actual IMAP INBOX.
 static int
 is_inbox( imap_store_t *ctx, const char *arg, int argl )
+{
+	if (!starts_with_upper( arg, argl, "INBOX", 5 ))
+		return 0;
+	if (arg[5] && arg[5] != ctx->delimiter[0])
+		return 0;
+	return 1;
+}
+
+// Use this to check whether a path fragment collides with the canonical INBOX.
+static int
+is_INBOX( imap_store_t *ctx, const char *arg, int argl )
 {
 	if (!starts_with( arg, argl, "INBOX", 5 ))
 		return 0;
@@ -1256,16 +1268,22 @@ parse_list_rsp_p2( imap_store_t *ctx, list_t *list, char *cmd ATTR_UNUSED )
 	}
 	arg = list->val;
 	argl = list->len;
-	if ((l = strlen( ctx->prefix ))) {
-		if (starts_with( arg, argl, ctx->prefix, l )) {
-			arg += l;
-			argl -= l;
-			if (is_inbox( ctx, arg, argl )) {
-				if (!arg[5])
-					warn( "IMAP warning: ignoring INBOX in %s\n", ctx->prefix );
-				goto skip;
-			}
-		} else if (!is_inbox( ctx, arg, argl )) {
+	if (is_inbox( ctx, arg, argl )) {
+		// The server might be weird and have a non-uppercase INBOX. It
+		// may legitimately do so, but we need the canonical spelling.
+		memcpy( arg, "INBOX", 5 );
+	} else if ((l = strlen( ctx->prefix ))) {
+		if (!starts_with( arg, argl, ctx->prefix, l ))
+			goto skip;
+		arg += l;
+		argl -= l;
+		// A folder named "INBOX" would be indistinguishable from the
+		// actual INBOX after prefix stripping, so drop it. This applies
+		// only to the fully uppercased spelling, as our canonical box
+		// names are case-sensitive (unlike IMAP's INBOX).
+		if (is_INBOX( ctx, arg, argl )) {
+			if (!arg[5])  // No need to complain about subfolders as well.
+				warn( "IMAP warning: ignoring INBOX in %s\n", ctx->prefix );
 			goto skip;
 		}
 	}
diff --git a/src/drv_maildir.c b/src/drv_maildir.c
index 8818d2e..e1622d3 100644
--- a/src/drv_maildir.c
+++ b/src/drv_maildir.c
@@ -352,6 +352,7 @@ maildir_list_maildirpp( maildir_store_t *ctx, int flags, const char *inbox )
 		} else {
 			if (!(flags & (LIST_PATH | LIST_PATH_MAYBE)))
 				continue;
+			// Explained in maildir_list_recurse().
 			if (starts_with( ent, -1, "INBOX", 5 ) && (!ent[5] || ent[5] == '.')) {
 				if (!warned) {
 					warned = 1;
@@ -437,6 +438,10 @@ maildir_list_recurse( maildir_store_t *ctx, int isBox, int flags,
 						continue;
 				}
 			}
+			// A folder named "INBOX" would be indistinguishable from the
+			// actual INBOX after prefix stripping, so drop it. This applies
+			// only to the fully uppercased spelling, as our canonical box
+			// names are case-sensitive (unlike IMAP's INBOX).
 			if (!nameLen && equals( ent, -1, "INBOX", 5 )) {
 				path[pathLen] = 0;
 				warn( "Maildir warning: ignoring INBOX in %s\n", path );