move the email address syntax validation for users and aliases into my new email_validator library (https://github.com/JoshData/python-email-validator)

management/mailconfig.py

@@ -2,6 +2,7 @@
 
 import subprocess, shutil, os, sqlite3, re
 import utils
+from email_validator import validate_email as validate_email_, EmailNotValidError
 
 def validate_email(email, mode=None):
 	# Checks that an email address is syntactically valid. Returns True/False.
@@ -15,59 +16,24 @@ def validate_email(email, mode=None):
 	# When mode=="alias", we're allowing anything that can be in a Postfix
 	# alias table, i.e. omitting the local part ("@domain.tld") is OK.
 
-	# Check that the address isn't absurdly long.
+	# Check the syntax of the address.
-	if len(email) > 255: return False
+	try:
+		validate_email_(email,
+			allow_smtputf8=False,
+			check_deliverability=False,
+			allow_empty_local=(mode=="alias")
+			)
+	except EmailNotValidError:
+		return False
 
 	if mode == 'user':
 		# There are a lot of characters permitted in email addresses, but
-		# Dovecot's sqlite driver seems to get confused if there are any
+		# Dovecot's sqlite auth driver seems to get confused if there are any
 		# unusual characters in the address. Bah. Also note that since
 		# the mailbox path name is based on the email address, the address
 		# shouldn't be absurdly long and must not have a forward slash.
-		ATEXT = r'[a-zA-Z0-9_\-]+'
+		if len(email) > 255: return False
-	elif mode in (None, 'alias'):
+		if re.search(r'[^\@\.a-zA-Z0-9_\-]+', email):
-		# For aliases, we can allow any valid email address.
-		# Based on RFC 2822 and https://github.com/SyrusAkbary/validate_email/blob/master/validate_email.py,
-		# these characters are permitted in email addresses.
-		ATEXT = r'[a-zA-Z0-9_!#$%&\'\*\+\-/=\?\^`\{\|\}~]+' # see 3.2.4
-	else:
-		raise ValueError(mode)
-
-	# per RFC 2822 3.2.4
-	DOT_ATOM_TEXT_LOCAL = ATEXT + r'(?:\.' + ATEXT + r')*'
-	if mode == 'alias':
-		# For aliases, Postfix accepts '@domain.tld' format for
-		# catch-all addresses on the source side and domain aliases
-		# on the destination side. Make the local part optional.
-		DOT_ATOM_TEXT_LOCAL = '(?:' + DOT_ATOM_TEXT_LOCAL + ')?'
-
-	# The domain part of the email address has a few more restrictions.
-
-	# In addition to the characters allowed by RFC 2822, the domain part
-	# must also satisfy the requirements of RFC 952/RFC 1123 which restrict
-	# the allowed characters of hostnames further. These are a subset of
-	# the Dovecot-allowed characters, fortunately. The hyphen cannot be at
-	# the beginning or end of a component of a hostname either, but we aren't
-	# testing that.
-	ATEXT2 = r'[a-zA-Z0-9\-]+'
-
-	# We can require that the host part have at least one period in it.
-	# We also know that all TLDs are at least two characters and end with a letter.
-	DOT_ATOM_TEXT_HOST = ATEXT2 + r'(?:\.' + ATEXT2 + r')*' + r'(?:\.' + ATEXT2 + r'[A-Za-z])'
-
-	# per RFC 2822 3.4.1
-	ADDR_SPEC = '^(%s)@(%s)$' % (DOT_ATOM_TEXT_LOCAL, DOT_ATOM_TEXT_HOST)
-
-	# Check the regular expression.
-	m = re.match(ADDR_SPEC, email)
-	if not m: return False
-
-	# Check that the domain part is valid IDNA.
-	localpart, domainpart = m.groups()
-	try:
-		domainpart.encode('ascii').decode("idna")
-	except:
-		# Domain is not valid IDNA.
 			return False
 
 	# Everything looks good.

setup/management.sh

@@ -3,7 +3,7 @@
 source setup/functions.sh
 
 apt_install python3-flask links duplicity libyaml-dev python3-dnspython python3-dateutil
-hide_output pip3 install rtyaml
+hide_output pip3 install rtyaml "email_validator==0.1.0-rc1"
 
 # Create a backup directory and a random key for encrypting backups.
 mkdir -p $STORAGE_ROOT/backup