Add domain maps from Unicode forms of internationalized domains to their ASCII forms

When an email is received by Postfix using SMTPUTF8 and the recipient domain is a Unicode internationalized domain, it was failing to be delivered (bouncing with 'relay access denied') because our users and aliases tables only store ASCII (IDNA) forms of internationalized domains. In this commit, domain maps are added to the auto_aliases table from the Unicode form of each mail domain to its IDNA form, if those forms are different. The Postfix domains query is updated to look at the auto_aliases table now as well, since it is the only table with Unicode forms of the mail domains.

However, mail delivery is still not working since the Dovecot LMTP server does not support SMTPUTF8, and mail still bounces but with an error that SMTPUTF8 is not supported.

management/mailconfig.py

@@ -218,6 +218,9 @@ def get_mail_aliases_ex(env):
 
 	domains = {}
 	for address, forwards_to, permitted_senders, auto in get_mail_aliases(env):
+		# skip auto domain maps since these are not informative in the control panel's aliases list
+		if auto and address.startswith("@"): continue
+
 		# get alias info
 		domain = get_domain(address)
 
@@ -259,11 +262,12 @@ def get_domain(emailaddr, as_unicode=True):
 def get_mail_domains(env, filter_aliases=lambda alias : True, users_only=False):
 	# Returns the domain names (IDNA-encoded) of all of the email addresses
 	# configured on the system. If users_only is True, only return domains
-	# with email addresses that correspond to user accounts.
+	# with email addresses that correspond to user accounts. Exclude Unicode
+	# forms of domain names listed in the automatic aliases table.
 	domains = []
 	domains.extend([get_domain(login, as_unicode=False) for login in get_mail_users(env)])
 	if not users_only:
-		domains.extend([get_domain(address, as_unicode=False) for address, *_ in get_mail_aliases(env) if filter_aliases(address) ])
+		domains.extend([get_domain(address, as_unicode=False) for address, _, _, auto in get_mail_aliases(env) if filter_aliases(address) and not auto ])
 	return set(domains)
 
 def add_mail_user(email, pw, privs, env):
@@ -569,6 +573,14 @@ def kick(env, mail_result=None):
 		if alias == administrator: continue # don't make an alias from the administrator to itself --- this alias must be created manually
 		auto_aliases[alias] = administrator
 
+	# Add domain maps from Unicode forms of IDNA domains to the ASCII forms stored in the alias table.
+	for domain in get_mail_domains(env):
+		try:
+			domain_unicode = idna.decode(domain.encode("ascii"))
+			if domain == domain_unicode: continue # not an IDNA/Unicode domain
+			auto_aliases["@" + domain_unicode] = "@" + domain
+		except (ValueError, UnicodeError, idna.IDNAError):
+			continue
 
 	add_auto_aliases(auto_aliases, env)
 

setup/mail-users.sh

@@ -111,7 +111,7 @@ tools/editconf.py /etc/postfix/main.cf \
 # SQL statement to check if we handle incoming mail for a domain, either for users or aliases.
 cat > /etc/postfix/virtual-mailbox-domains.cf << EOF;
 dbpath=$db_path
-query = SELECT 1 FROM users WHERE email LIKE '%%@%s' UNION SELECT 1 FROM aliases WHERE source LIKE '%%@%s'
+query = SELECT 1 FROM users WHERE email LIKE '%%@%s' UNION SELECT 1 FROM aliases WHERE source LIKE '%%@%s' UNION SELECT 1 FROM auto_aliases WHERE source LIKE '%%@%s'
 EOF
 
 # SQL statement to check if we handle incoming mail for a user.