commit f77a2b6c3ffe2ea96f4a4b05ec38dc9d53266ecb
Author: Timo Sirainen <timo.sirainen@open-xchange.com>
Date:   Wed May 27 11:35:55 2020 +0300

    lib-mail: Fix parse_too_many_nested_mime_parts()
    
    This was originally correct, until it was "optimized" wrong and got merged.

diff --git a/src/lib-mail/message-parser.c b/src/lib-mail/message-parser.c
index 175d4b488..5b11772ff 100644
--- a/src/lib-mail/message-parser.c
+++ b/src/lib-mail/message-parser.c
@@ -621,7 +621,7 @@ static bool block_is_at_eoh(const struct message_block *block)
 
 static bool parse_too_many_nested_mime_parts(struct message_parser_ctx *ctx)
 {
-	return ctx->nested_parts_count > ctx->max_nested_mime_parts;
+	return ctx->nested_parts_count+1 >= ctx->max_nested_mime_parts;
 }
 
 #define MUTEX_FLAGS \