#!/usr/local/lib/mailinabox/env/bin/python

# NOTE:
# This script is run both using the system-wide Python 3
# interpreter (/usr/bin/python3) as well as through the
# virtualenv (/usr/local/lib/mailinabox/env). So only
# import packages at the top level of this script that
# are installed in *both* contexts. We use the system-wide
# Python 3 in setup/questions.sh to validate the email
# address entered by the user.

import subprocess
import shutil
import os
import sqlite3
import re
import utils
from email_validator import validate_email as validate_email_, EmailNotValidError
import idna


def validate_email(email, mode=None):
	# Checks that an email address is syntactically valid. Returns True/False.
	# An email address may contain ASCII characters only because Dovecot's
	# authentication mechanism gets confused with other character encodings.
	#
	# When mode=="user", we're checking that this can be a user account name.
	# Dovecot has tighter restrictions - letters, numbers, underscore, and
	# dash only!
	#
	# 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 the syntax of the address.
	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 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.
		# Our database is case sensitive (oops), which affects mail delivery
		# (Postfix always queries in lowercase?), so also only permit lowercase
		# letters.
		if len(email) > 255:
			return False
		if re.search(r'[^\@\.a-z0-9_\-]+', email):
			return False

	# Everything looks good.
	return True


def sanitize_idn_email_address(email):
	# The user may enter Unicode in an email address. Convert the domain part
	# to IDNA before going into our database. Leave the local part alone ---
	# although validate_email will reject non-ASCII characters.
	#
	# The domain name system only exists in ASCII, so it doesn't make sense
	# to store domain names in Unicode. We want to store what is meaningful
	# to the underlying protocols.
	try:
		localpart, domainpart = email.split("@")
		domainpart = idna.encode(domainpart).decode('ascii')
		return localpart + "@" + domainpart
	except (ValueError, idna.IDNAError):
		# ValueError: String does not have a single @-sign, so it is not
		# a valid email address. IDNAError: Domain part is not IDNA-valid.
		# Validation is not this function's job, so return value unchanged.
		# If there are non-ASCII characters it will be filtered out by
		# validate_email.
		return email


def prettify_idn_email_address(email):
	# This is the opposite of sanitize_idn_email_address. We store domain
	# names in IDNA in the database, but we want to show Unicode to the user.
	try:
		localpart, domainpart = email.split("@")
		domainpart = idna.decode(domainpart.encode("ascii"))
		return localpart + "@" + domainpart
	except (ValueError, UnicodeError, idna.IDNAError):
		# Failed to decode IDNA, or the email address does not have a
		# single @-sign. Should never happen.
		return email


def is_dcv_address(email):
	email = email.lower()
	for localpart in ("admin", "administrator", "postmaster", "hostmaster",
					"webmaster", "abuse"):
		if email.startswith(localpart + "@") or email.startswith(localpart +
																"+"):
			return True
	return False


def open_database(env, with_connection=False):
	conn = sqlite3.connect(env["STORAGE_ROOT"] + "/mail/users.sqlite")
	if not with_connection:
		return conn.cursor()
	else:
		return conn, conn.cursor()


def get_mail_users(env):
	# Returns a flat, sorted list of all user accounts.
	c = open_database(env)
	c.execute('SELECT email FROM users')
	users = [row[0] for row in c.fetchall()]
	return utils.sort_email_addresses(users, env)


def sizeof_fmt(num):
	for unit in ['', 'K', 'M', 'G', 'T']:
		if abs(num) < 1024.0:
			if abs(num) > 99:
				return "%3.0f%s" % (num, unit)
			else:
				return "%2.1f%s" % (num, unit)

		num /= 1024.0

	return str(num)


def get_mail_users_ex(env, with_archived=False):
	# Returns a complex data structure of all user accounts, optionally
	# including archived (status="inactive") accounts.
	#
	# [
	#   {
	#     domain: "domain.tld",
	#     users: [
	#       {
	#         email: "name@domain.tld",
	#         privileges: [ "priv1", "priv2", ... ],
	#         status: "active" | "inactive",
	#       },
	#       ...
	#     ]
	#   },
	#   ...
	# ]

	# Get users and their privileges.
	users = []
	active_accounts = set()
	c = open_database(env)
	c.execute('SELECT email, privileges, quota FROM users')
	for email, privileges, quota in c.fetchall():
		active_accounts.add(email)

		(user, domain) = email.split('@')
		box_size = 0
		box_count = 0
		box_quota = 0
		percent = ''
		try:
			dirsize_file = os.path.join(
				env['STORAGE_ROOT'],
				'mail/mailboxes/%s/%s/maildirsize' % (domain, user))
			with open(dirsize_file, 'r') as f:
				box_quota = int(f.readline().split('S')[0])
				for line in f.readlines():
					(size, count) = line.split(' ')
					box_size += int(size)
					box_count += int(count)

			try:
				percent = (box_size / box_quota) * 100
			except:
				percent = 'Error'

		except:
			box_size = '?'
			box_count = '?'
			box_quota = '?'
			percent = '?'

		if quota == '0':
			percent = ''

		user = {
			"email": email,
			"privileges": parse_privs(privileges),
			"quota": quota,
			"box_quota": box_quota,
			"box_size": sizeof_fmt(box_size) if box_size != '?' else box_size,
			"percent":
			'%3.0f%%' % percent if type(percent) != str else percent,
			"box_count": box_count,
			"status": "active",
		}
		users.append(user)

	# Add in archived accounts.
	if with_archived:
		root = os.path.join(env['STORAGE_ROOT'], 'mail/mailboxes')
		for domain in os.listdir(root):
			if os.path.isdir(os.path.join(root, domain)):
				for user in os.listdir(os.path.join(root, domain)):
					email = user + "@" + domain
					mbox = os.path.join(root, domain, user)
					if email in active_accounts:
						continue
					user = {
						"email": email,
						"privileges": [],
						"status": "inactive",
						"mailbox": mbox,
						"box_count": '?',
						"box_size": '?',
						"box_quota": '?',
						"percent": '?',
					}
					users.append(user)

	# Group by domain.
	domains = {}
	for user in users:
		domain = get_domain(user["email"])
		if domain not in domains:
			domains[domain] = {"domain": domain, "users": []}
		domains[domain]["users"].append(user)

	# Sort domains.
	domains = [
		domains[domain] for domain in utils.sort_domains(domains.keys(), env)
	]

	# Sort users within each domain first by status then lexicographically by email address.
	for domain in domains:
		domain["users"].sort(
			key=lambda user: (user["status"] != "active", user["email"]))

	return domains


def get_admins(env):
	# Returns a set of users with admin privileges.
	users = set()
	for domain in get_mail_users_ex(env):
		for user in domain["users"]:
			if "admin" in user["privileges"]:
				users.add(user["email"])
	return users


def get_mail_aliases(env):
	# Returns a sorted list of tuples of (address, forward-tos, permitted-senders, auto).
	c = open_database(env)
	c.execute(
		'SELECT source, destination, permitted_senders, 0 as auto FROM aliases UNION SELECT source, destination, permitted_senders, 1 as auto FROM auto_aliases'
	)
	aliases = {row[0]: row for row in c.fetchall()}  # make dict

	# put in a canonical order: sort by domain, then by email address lexicographically
	aliases = [
		aliases[address]
		for address in utils.sort_email_addresses(aliases.keys(), env)
	]
	return aliases


def get_mail_aliases_ex(env):
	# Returns a complex data structure of all mail aliases, similar
	# to get_mail_users_ex.
	#
	# [
	#   {
	#     domain: "domain.tld",
	#     alias: [
	#       {
	#         address: "name@domain.tld", # IDNA-encoded
	#         address_display: "name@domain.tld", # full Unicode
	#         forwards_to: ["user1@domain.com", "receiver-only1@domain.com", ...],
	#         permitted_senders: ["user1@domain.com", "sender-only1@domain.com", ...] OR null,
	#         auto: True|False
	#       },
	#       ...
	#     ]
	#   },
	#   ...
	# ]

	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)

		# add to list
		if not domain in domains:
			domains[domain] = {
				"domain": domain,
				"aliases": [],
			}
		domains[domain]["aliases"].append({
			"address":
			address,
			"address_display":
			prettify_idn_email_address(address),
			"forwards_to": [
				prettify_idn_email_address(r.strip())
				for r in forwards_to.split(",")
			],
			"permitted_senders": [
				prettify_idn_email_address(s.strip())
				for s in permitted_senders.split(",")
			] if permitted_senders is not None else None,
			"auto":
			bool(auto),
		})

	# Sort domains.
	domains = [
		domains[domain] for domain in utils.sort_domains(domains.keys(), env)
	]

	# Sort aliases within each domain first by required-ness then lexicographically by address.
	for domain in domains:
		domain["aliases"].sort(
			key=lambda alias: (alias["auto"], alias["address"]))
	return domains


def get_noreply_addresses(env):
	# Returns a set of noreply addresses:
	# Noreply addresses are a special type of addresses that are send-only.
	# Mail sent to these addresses is automatically bounced with a customized message..
	c = open_database(env)
	c.execute('SELECT email FROM noreply')
	return set(row[0] for row in c.fetchall())


def get_domain(emailaddr, as_unicode=True):
	# Gets the domain part of an email address. Turns IDNA
	# back to Unicode for display.
	ret = emailaddr.split('@', 1)[1]
	if as_unicode:
		try:
			ret = idna.decode(ret.encode('ascii'))
		except (ValueError, UnicodeError, idna.IDNAError):
			# Looks like we have an invalid email address in
			# the database. Now is not the time to complain.
			pass
	return ret


def get_all_mail_addresses(env, no_catchalls=True):
	# Gets the email addresses on literally all tables (users, aliases and noreplies)
	emails = get_mail_users(env)
	emails.extend([a[0] for a in get_mail_aliases(env)])
	emails.extend(get_noreply_addresses(env))

	# Filter out catch-alls
	if no_catchalls:
		return set(filter(lambda e: e.split("@")[0].strip != "", emails))

	return set(emails)


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. 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, _, _, auto in get_mail_aliases(env)
			if filter_aliases(address) and not auto
		])
		domains.extend([
			get_domain(address, as_unicode=False)
			for address in get_noreply_addresses(env)
		])
	return set(domains)


def add_mail_user(email, pw, privs, quota, env):
	# validate email
	if email.strip() == "":
		return ("No email address provided.", 400)
	elif not validate_email(email):
		return ("Invalid email address.", 400)
	elif not validate_email(email, mode='user'):
		return (
			"User account email addresses may only use the lowercase ASCII letters a-z, the digits 0-9, underscore (_), hyphen (-), and period (.).",
			400)
	elif is_dcv_address(email) and len(get_mail_users(env)) > 0:
		# Make domain control validation hijacking a little harder to mess up by preventing the usual
		# addresses used for DCV from being user accounts. Except let it be the first account because
		# during box setup the user won't know the rules.
		return (
			"You may not make a user account for that address because it is frequently used for domain control validation. Use an alias instead if necessary.",
			400)

	# validate password
	validate_password(pw)

	# validate privileges
	if privs is None or privs.strip() == "":
		privs = []
	else:
		privs = privs.split("\n")
		for p in privs:
			validation = validate_privilege(p)
			if validation:
				return validation

	if quota is None:
		quota = get_default_quota()

	try:
		quota = validate_quota(quota)
	except ValueError as e:
		return (str(e), 400)

	# get the database
	conn, c = open_database(env, with_connection=True)

	# hash the password
	pw = hash_password(pw)

	# add the user to the database
	try:
		c.execute(
			"INSERT INTO users (email, password, privileges, quota) VALUES (?, ?, ?, ?)",
			(email, pw, "\n".join(privs), quota))
	except sqlite3.IntegrityError:
		return ("User already exists.", 400)

	# write databasebefore next step
	conn.commit()

	dovecot_quota_recalc(email)

	# Update things in case any new domains are added.
	return kick(env, "mail user added")


def set_mail_password(email, pw, env):
	# validate that password is acceptable
	validate_password(pw)

	# hash the password
	pw = hash_password(pw)

	# update the database
	conn, c = open_database(env, with_connection=True)
	c.execute("UPDATE users SET password=? WHERE email=?", (pw, email))
	if c.rowcount != 1:
		return ("That's not a user (%s)." % email, 400)
	conn.commit()
	return "OK"


def hash_password(pw):
	# Turn the plain password into a Dovecot-format hashed password, meaning
	# something like "{SCHEME}hashedpassworddata".
	# http://wiki2.dovecot.org/Authentication/PasswordSchemes
	return utils.shell(
		'check_output',
		["/usr/bin/doveadm", "pw", "-s", "SHA512-CRYPT", "-p", pw]).strip()


def get_mail_quota(email, env):
	conn, c = open_database(env, with_connection=True)
	c.execute("SELECT quota FROM users WHERE email=?", (email, ))
	rows = c.fetchall()
	if len(rows) != 1:
		return ("That's not a user (%s)." % email, 400)

	return rows[0][0]


def set_mail_quota(email, quota, env):
	# validate that password is acceptable
	quota = validate_quota(quota)

	# update the database
	conn, c = open_database(env, with_connection=True)
	c.execute("UPDATE users SET quota=? WHERE email=?", (quota, email))
	if c.rowcount != 1:
		return ("That's not a user (%s)." % email, 400)
	conn.commit()

	dovecot_quota_recalc(email)

	return "OK"


def dovecot_quota_recalc(email):
	# dovecot processes running for the user will not recognize the new quota setting
	# a reload is necessary to reread the quota setting, but it will also shut down
	# running dovecot processes.  Email clients generally log back in when they lose
	# a connection.
	# subprocess.call(['doveadm', 'reload'])

	# force dovecot to recalculate the quota info for the user.
	subprocess.call(["doveadm", "quota", "recalc", "-u", email])


def get_default_quota(env):
	config = utils.load_settings(env)
	return config.get("default-quota", '0')


def validate_quota(quota):
	# validate quota
	quota = quota.strip().upper()

	if quota == "":
		raise ValueError("No quota provided.")
	if re.search(r"[\s,.]", quota):
		raise ValueError(
			"Quotas cannot contain spaces, commas, or decimal points.")
	if not re.match(r'^[\d]+[GM]?$', quota):
		raise ValueError("Invalid quota.")

	return quota


def get_mail_password(email, env):
	# Gets the hashed password for a user. Passwords are stored in Dovecot's
	# password format, with a prefixed scheme.
	# http://wiki2.dovecot.org/Authentication/PasswordSchemes
	# update the database
	c = open_database(env)
	c.execute('SELECT password FROM users WHERE email=?', (email, ))
	rows = c.fetchall()
	if len(rows) != 1:
		raise ValueError("That's not a user (%s)." % email)
	return rows[0][0]


def remove_mail_user(email, env):
	# remove
	conn, c = open_database(env, with_connection=True)
	c.execute("DELETE FROM users WHERE email=?", (email, ))
	if c.rowcount != 1:
		return ("That's not a user (%s)." % email, 400)
	conn.commit()

	# Update things in case any domains are removed.
	return kick(env, "mail user removed")


def parse_privs(value):
	return [p for p in value.split("\n") if p.strip() != ""]


def get_mail_user_privileges(email, env, empty_on_error=False):
	# get privs
	c = open_database(env)
	c.execute('SELECT privileges FROM users WHERE email=?', (email, ))
	rows = c.fetchall()
	if len(rows) != 1:
		if empty_on_error:
			return []
		return ("That's not a user (%s)." % email, 400)
	return parse_privs(rows[0][0])


def validate_privilege(priv):
	if "\n" in priv or priv.strip() == "":
		return ("That's not a valid privilege (%s)." % priv, 400)
	return None


def add_remove_mail_user_privilege(email, priv, action, env):
	# validate
	validation = validate_privilege(priv)
	if validation:
		return validation

	# get existing privs, but may fail
	privs = get_mail_user_privileges(email, env)
	if isinstance(privs, tuple):
		return privs  # error

	# update privs set
	if action == "add":
		if priv not in privs:
			privs.append(priv)
	elif action == "remove":
		privs = [p for p in privs if p != priv]
	else:
		return ("Invalid action.", 400)

	# commit to database
	conn, c = open_database(env, with_connection=True)
	c.execute("UPDATE users SET privileges=? WHERE email=?",
			("\n".join(privs), email))
	if c.rowcount != 1:
		return ("Something went wrong.", 400)
	conn.commit()

	return "OK"


def add_mail_alias(address,
				forwards_to,
				permitted_senders,
				env,
				update_if_exists=False,
				do_kick=True):
	# convert Unicode domain to IDNA
	address = sanitize_idn_email_address(address)

	# Our database is case sensitive (oops), which affects mail delivery
	# (Postfix always queries in lowercase?), so force lowercase.
	address = address.lower()

	# validate address
	address = address.strip()
	if address == "":
		return ("No email address provided.", 400)
	if not validate_email(address, mode='alias'):
		return ("Invalid email address (%s)." % address, 400)

	# validate forwards_to
	validated_forwards_to = []
	forwards_to = forwards_to.strip()

	# extra checks for email addresses used in domain control validation
	is_dcv_source = is_dcv_address(address)

	# Postfix allows a single @domain.tld as the destination, which means
	# the local part on the address is preserved in the rewrite. We must
	# try to convert Unicode to IDNA first before validating that it's a
	# legitimate alias address. Don't allow this sort of rewriting for
	# DCV source addresses.
	r1 = sanitize_idn_email_address(forwards_to)
	if validate_email(r1, mode='alias') and not is_dcv_source:
		validated_forwards_to.append(r1)

	else:
		# Parse comma and \n-separated destination emails & validate. In this
		# case, the forwards_to must be complete email addresses.
		for line in forwards_to.split("\n"):
			for email in line.split(","):
				email = email.strip()
				if email == "":
					continue
				email = sanitize_idn_email_address(email)  # Unicode => IDNA
				# Strip any +tag from email alias and check privileges
				privileged_email = re.sub(r"(?=\+)[^@]*(?=@)", '', email)
				if not validate_email(email):
					return ("Invalid receiver email address (%s)." % email,
							400)
				if is_dcv_source and not is_dcv_address(
					email) and "admin" not in get_mail_user_privileges(
						privileged_email, env, empty_on_error=True):
					# Make domain control validation hijacking a little harder to mess up by
					# requiring aliases for email addresses typically used in DCV to forward
					# only to accounts that are administrators on this system.
					return (
						"This alias can only have administrators of this system as destinations because the address is frequently used for domain control validation.",
						400)
				validated_forwards_to.append(email)

	# validate permitted_senders
	valid_logins = get_mail_users(env)
	validated_permitted_senders = []
	permitted_senders = permitted_senders.strip()

	# Parse comma and \n-separated sender logins & validate. The permitted_senders must be
	# valid usernames.
	for line in permitted_senders.split("\n"):
		for login in line.split(","):
			login = login.strip()
			if login == "":
				continue
			if login not in valid_logins:
				return (
					"Invalid permitted sender: %s is not a user on this system."
					% login, 400)
			validated_permitted_senders.append(login)

	# Make sure the alias has either a forwards_to or a permitted_sender.
	if len(validated_forwards_to) + len(validated_permitted_senders) == 0:
		return (
			"The alias must either forward to an address or have a permitted sender.",
			400)

	# save to db

	forwards_to = ",".join(validated_forwards_to)

	if len(validated_permitted_senders) == 0:
		permitted_senders = None
	else:
		permitted_senders = ",".join(validated_permitted_senders)

	conn, c = open_database(env, with_connection=True)
	try:
		c.execute(
			"INSERT INTO aliases (source, destination, permitted_senders) VALUES (?, ?, ?)",
			(address, forwards_to, permitted_senders))
		return_status = "alias added"
	except sqlite3.IntegrityError:
		if not update_if_exists:
			return ("Alias already exists (%s)." % address, 400)
		else:
			c.execute(
				"UPDATE aliases SET destination = ?, permitted_senders = ? WHERE source = ?",
				(forwards_to, permitted_senders, address))
			return_status = "alias updated"

	conn.commit()

	if do_kick:
		# Update things in case any new domains are added.
		return kick(env, return_status)


def remove_mail_alias(address, env, do_kick=True):
	# convert Unicode domain to IDNA
	address = sanitize_idn_email_address(address)

	# remove
	conn, c = open_database(env, with_connection=True)
	c.execute("DELETE FROM aliases WHERE source=?", (address, ))
	if c.rowcount != 1:
		return ("That's not an alias (%s)." % address, 400)
	conn.commit()

	if do_kick:
		# Update things in case any domains are removed.
		return kick(env, "alias removed")


def add_auto_aliases(aliases, env):
	conn, c = open_database(env, with_connection=True)
	c.execute("DELETE FROM auto_aliases")
	for source, destination in aliases.items():
		c.execute(
			"INSERT INTO auto_aliases (source, destination) VALUES (?, ?)",
			(source, destination))
	conn.commit()


def get_system_administrator(env):
	return "administrator@" + env['PRIMARY_HOSTNAME']


def get_required_aliases(env):
	# These are the aliases that must exist.
	aliases = set()

	# The system administrator alias is required.
	aliases.add(get_system_administrator(env))

	# The hostmaster alias is exposed in the DNS SOA for each zone.
	aliases.add("hostmaster@" + env['PRIMARY_HOSTNAME'])

	# Get a list of domains we serve mail for, except ones for which the only
	# email on that domain are the required aliases or a catch-all/domain-forwarder.
	real_mail_domains = get_mail_domains(
		env,
		filter_aliases=lambda alias: not alias.startswith("postmaster@") and
		not alias.startswith("admin@") and not alias.startswith(
			"abuse@") and not alias.startswith("@"))

	# Create postmaster@, admin@ and abuse@ for all domains we serve
	# mail on. postmaster@ is assumed to exist by our Postfix configuration.
	# admin@isn't anything, but it might save the user some trouble e.g. when
	# buying an SSL certificate.
	# abuse@ is part of RFC2142: https://www.ietf.org/rfc/rfc2142.txt
	for domain in real_mail_domains:
		aliases.add("postmaster@" + domain)
		aliases.add("admin@" + domain)
		aliases.add("abuse@" + domain)

	return aliases


def add_noreply_address(env, address, do_kick=True):
	email = sanitize_idn_email_address(address)
	# validate email
	if email.strip() == "":
		return ("No email address provided.", 400)
	elif not validate_email(email):
		return ("Invalid email address.", 400)

	# Make sure it's not an user/alias already
	if email in get_mail_users(env):
		return ("This address is already an user.", 400)
	elif email in get_mail_aliases(env):
		return ("This address is already an alias.", 400)

	ret = ""

	# Add the address
	conn, c = open_database(env, with_connection=True)
	try:
		c.execute("INSERT INTO noreply (email) VALUES (?)", (email, ))
		if do_kick:
			ret = kick(env, "No-reply address (%s) added" % address)
		else:
			ret = "No-reply address (%s) added" % address
	except sqlite3.IntegrityError:
		return ("This noreply (%s) already exists." % address, 400)

	conn.commit()
	return ret


def remove_noreply_address(env, address, do_kick=True):
	email = sanitize_idn_email_address(address)

	# yeet yeet deleet
	conn, c = open_database(env, with_connection=True)
	c.execute("DELETE FROM noreply WHERE email=?", (email, ))
	if c.rowcount != 1:
		return ("That's not a noreply (%s)." % address, 400)
	conn.commit()

	if do_kick:
		# Update things in case any domains are removed.
		return kick(env, "No-reply address removed")


def get_required_noreply_addresses(env):
	return {"noreply-daemon@" + env['PRIMARY_HOSTNAME']}


def kick(env, mail_result=None):
	results = []

	# Include the current operation's result in output.

	if mail_result is not None:
		results.append(mail_result + "\n")

	auto_aliases = {}

	# Mape required aliases to the administrator alias (which should be created manually).
	administrator = get_system_administrator(env)
	required_aliases = get_required_aliases(env)
	required_noreply = get_required_noreply_addresses(env)
	existing_noreply = get_noreply_addresses(env)
	for alias in required_aliases:
		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)
	for address in required_noreply - existing_noreply:
		add_noreply_address(env, address, do_kick=False)
		results.append("added noreply address \"%s\"\n" % address)

	# Remove auto-generated postmaster/admin/abuse alises from the main aliases table.
	# They are now stored in the auto_aliases table.
	for address, forwards_to, permitted_senders, auto in get_mail_aliases(env):
		user, domain = address.split("@")
		if user in ("postmaster", "admin", "abuse") \
							and address not in required_aliases \
							and forwards_to == get_system_administrator(env) \
							and not auto:
			remove_mail_alias(address, env, do_kick=False)
			results.append(
				"removed alias %s (was to %s; domain no longer used for email)\n"
				% (address, forwards_to))

	# Update DNS and nginx in case any domains are added/removed.

	from dns_update import do_dns_update
	results.append(do_dns_update(env))

	from web_update import do_web_update
	results.append(do_web_update(env))

	return "".join(s for s in results if s != "")


def validate_password(pw):
	# validate password
	if pw.strip() == "":
		raise ValueError("No password provided.")
	if len(pw) < 8:
		raise ValueError("Passwords must be at least eight characters.")


if __name__ == "__main__":
	import sys
	if len(sys.argv) > 2 and sys.argv[1] == "validate-email":
		# Validate that we can create a Dovecot account for a given string.
		if validate_email(sys.argv[2], mode='user'):
			sys.exit(0)
		else:
			sys.exit(1)

	if len(sys.argv) > 1 and sys.argv[1] == "update":
		from utils import load_environment
		print(kick(load_environment()))