From 78c25f8b6dc8c841c2200bab6bfcbf2071f2f3c1 Mon Sep 17 00:00:00 2001
From: elhoim <elhoim@gmail.com>
Date: Mon, 31 Aug 2026 00:02:06 +0000
Subject: [PATCH] Allow underscores in domain/hostname label regex

looks_like_domain() excluded underscores from its label character class, so DMARC/DKIM-style hostnames like _dmarc.example.com were never recognised as domains and no guess was offered for them. Add '_' to the label regex character class.
---
 bin/cli.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bin/cli.py b/bin/cli.py
index 92267b1..0d04e0f 100644
--- a/bin/cli.py
+++ b/bin/cli.py
@@ -156,7 +156,7 @@ def looks_like_domain(value: str) -> bool:
     labels = value.split(".")
     if len(labels) < 2:
         return False
-    label_re = re.compile(r"^[A-Za-z0-9-]{1,63}$")
+    label_re = re.compile(r"^[A-Za-z0-9_-]{1,63}$")
     return all(
         label_re.match(label) and not label.startswith("-") and not label.endswith("-")
         for label in labels