diff --git a/src/Products/EasyNewsletter/config.py b/src/Products/EasyNewsletter/config.py
index 6d4f0d52..a14b3942 100644
--- a/src/Products/EasyNewsletter/config.py
+++ b/src/Products/EasyNewsletter/config.py
@@ -53,7 +53,7 @@
 
 
 EMAIL_RE = re.compile(
-    r"(?:^|\s)[-a-z0-9_.]+@(?:[-a-z0-9]+\.)+[a-z]{2,6}(?:\s|$)", re.IGNORECASE)
+    r"(?:^|\s)[-a-z0-9_.]+@(?:[-a-z0-9]+\.)+[a-z]{2,63}(?:\s|$)", re.IGNORECASE)
 
 
 DEFAULT_SUBSCRIBER_CONFIRMATION_MAIL_SUBJECT = _(