Modify email mirror regular expression to match messages sent to any zulip.net server

(imported from commit 733a2ff2586c6c4bbe6536a3c42973726c8adb14)

zerver/lib/actions.py

@@ -1847,6 +1847,9 @@ def encode_email_address_helper(name, email_token):
 def decode_email_address(email):
     # Perform the reverse of encode_email_address. Returns a tuple of (streamname, email_token)
     pattern_parts = [re.escape(part) for part in settings.EMAIL_GATEWAY_PATTERN.split('%s')]
+    if settings.DEPLOYED and not settings.ENTERPRISE:
+        # Accept mails delivered to any Zulip server
+        pattern_parts[-1] = r'@[\w-]*\.zulip\.net'
     match_email_re = re.compile("(.*?)".join(pattern_parts))
     match = match_email_re.match(email)