app-MAIL-temp/app/email_utils.py
2020-07-23 11:32:11 +02:00

531 lines
15 KiB
Python

import email
import os
from email.header import decode_header
from email.message import Message
from email.mime.base import MIMEBase
from email.mime.multipart import MIMEMultipart
from email.mime.text import MIMEText
from email.utils import make_msgid, formatdate, parseaddr
from smtplib import SMTP
from typing import Optional
import arrow
import dkim
from jinja2 import Environment, FileSystemLoader
from app.config import (
SUPPORT_EMAIL,
ROOT_DIR,
POSTFIX_SERVER,
NOT_SEND_EMAIL,
DKIM_SELECTOR,
DKIM_PRIVATE_KEY,
DKIM_HEADERS,
ALIAS_DOMAINS,
SUPPORT_NAME,
POSTFIX_SUBMISSION_TLS,
MAX_NB_EMAIL_FREE_PLAN,
DISPOSABLE_EMAIL_DOMAINS,
MAX_ALERT_24H,
POSTFIX_PORT,
SENDER,
)
from app.dns_utils import get_mx_domains
from app.extensions import db
from app.log import LOG
from app.models import Mailbox, User, SentAlert
def render(template_name, **kwargs) -> str:
templates_dir = os.path.join(ROOT_DIR, "templates", "emails")
env = Environment(loader=FileSystemLoader(templates_dir))
template = env.get_template(template_name)
return template.render(MAX_NB_EMAIL_FREE_PLAN=MAX_NB_EMAIL_FREE_PLAN, **kwargs)
def send_welcome_email(user):
send_email(
user.email,
f"Welcome to SimpleLogin {user.name}",
render("com/welcome.txt", name=user.name, user=user),
render("com/welcome.html", name=user.name, user=user),
)
def send_trial_end_soon_email(user):
send_email(
user.email,
f"Your trial will end soon {user.name}",
render("transactional/trial-end.txt", name=user.name, user=user),
render("transactional/trial-end.html", name=user.name, user=user),
)
def send_activation_email(email, name, activation_link):
send_email(
email,
f"Just one more step to join SimpleLogin {name}",
render(
"transactional/activation.txt",
name=name,
activation_link=activation_link,
email=email,
),
render(
"transactional/activation.html",
name=name,
activation_link=activation_link,
email=email,
),
)
def send_reset_password_email(email, name, reset_password_link):
send_email(
email,
f"Reset your password on SimpleLogin",
render(
"transactional/reset-password.txt",
name=name,
reset_password_link=reset_password_link,
),
render(
"transactional/reset-password.html",
name=name,
reset_password_link=reset_password_link,
),
)
def send_change_email(new_email, current_email, name, link):
send_email(
new_email,
f"Confirm email update on SimpleLogin",
render(
"transactional/change-email.txt",
name=name,
link=link,
new_email=new_email,
current_email=current_email,
),
render(
"transactional/change-email.html",
name=name,
link=link,
new_email=new_email,
current_email=current_email,
),
)
def send_new_app_email(email, name):
send_email(
email,
f"Any question/feedback for SimpleLogin {name}?",
render("com/new-app.txt", name=name),
render("com/new-app.html", name=name),
)
def send_test_email_alias(email, name):
send_email(
email,
f"This email is sent to {email}",
render("transactional/test-email.txt", name=name, alias=email),
render("transactional/test-email.html", name=name, alias=email),
)
def send_cannot_create_directory_alias(user, alias, directory):
"""when user cancels their subscription, they cannot create alias on the fly.
If this happens, send them an email to notify
"""
send_email(
user.email,
f"Alias {alias} cannot be created",
render(
"transactional/cannot-create-alias-directory.txt",
name=user.name,
alias=alias,
directory=directory,
),
render(
"transactional/cannot-create-alias-directory.html",
name=user.name,
alias=alias,
directory=directory,
),
)
def send_cannot_create_domain_alias(user, alias, domain):
"""when user cancels their subscription, they cannot create alias on the fly with custom domain.
If this happens, send them an email to notify
"""
send_email(
user.email,
f"Alias {alias} cannot be created",
render(
"transactional/cannot-create-alias-domain.txt",
name=user.name,
alias=alias,
domain=domain,
),
render(
"transactional/cannot-create-alias-domain.html",
name=user.name,
alias=alias,
domain=domain,
),
)
def send_email(to_email, subject, plaintext, html=None):
if NOT_SEND_EMAIL:
LOG.d(
"send email with subject %s to %s, plaintext: %s",
subject,
to_email,
plaintext,
)
return
LOG.d("send email to %s, subject %s", to_email, subject)
if POSTFIX_SUBMISSION_TLS:
smtp = SMTP(POSTFIX_SERVER, 587)
smtp.starttls()
else:
smtp = SMTP(POSTFIX_SERVER, POSTFIX_PORT or 25)
msg = MIMEMultipart("alternative")
msg.attach(MIMEText(plaintext, "text"))
if not html:
html = plaintext.replace("\n", "<br>")
msg.attach(MIMEText(html, "html"))
msg["Subject"] = subject
msg["From"] = f"{SUPPORT_NAME} <{SUPPORT_EMAIL}>"
msg["To"] = to_email
msg_id_header = make_msgid()
msg["Message-ID"] = msg_id_header
date_header = formatdate()
msg["Date"] = date_header
# add DKIM
email_domain = SUPPORT_EMAIL[SUPPORT_EMAIL.find("@") + 1 :]
add_dkim_signature(msg, email_domain)
msg_raw = msg.as_bytes()
if SENDER:
smtp.sendmail(SENDER, to_email, msg_raw)
else:
smtp.sendmail(SUPPORT_EMAIL, to_email, msg_raw)
def send_email_with_rate_control(
user: User,
alert_type: str,
to_email: str,
subject,
plaintext,
html=None,
max_alert_24h=MAX_ALERT_24H,
) -> bool:
"""Same as send_email with rate control over alert_type.
For now no more than _MAX_ALERT_24h alert can be sent in the last 24h
Return true if the email is sent, otherwise False
"""
to_email = to_email.lower().strip()
one_day_ago = arrow.now().shift(days=-1)
nb_alert = (
SentAlert.query.filter_by(alert_type=alert_type, to_email=to_email)
.filter(SentAlert.created_at > one_day_ago)
.count()
)
if nb_alert >= max_alert_24h:
LOG.warning(
"%s emails were sent to %s in the last 24h, alert type %s",
nb_alert,
to_email,
alert_type,
)
return False
SentAlert.create(user_id=user.id, alert_type=alert_type, to_email=to_email)
db.session.commit()
send_email(to_email, subject, plaintext, html)
return True
def get_email_local_part(address):
"""
Get the local part from email
ab@cd.com -> ab
"""
return address[: address.find("@")]
def get_email_domain_part(address):
"""
Get the domain part from email
ab@cd.com -> cd.com
"""
return address[address.find("@") + 1 :].strip().lower()
def add_dkim_signature(msg: Message, email_domain: str):
delete_header(msg, "DKIM-Signature")
# Specify headers in "byte" form
# Generate message signature
sig = dkim.sign(
msg.as_bytes(),
DKIM_SELECTOR,
email_domain.encode(),
DKIM_PRIVATE_KEY.encode(),
include_headers=DKIM_HEADERS,
)
sig = sig.decode()
# remove linebreaks from sig
sig = sig.replace("\n", " ").replace("\r", "")
msg["DKIM-Signature"] = sig[len("DKIM-Signature: ") :]
def add_or_replace_header(msg: Message, header: str, value: str):
"""
Remove all occurrences of `header` and add `header` with `value`.
"""
delete_header(msg, header)
msg[header] = value
def delete_header(msg: Message, header: str):
"""a header can appear several times in message."""
# inspired from https://stackoverflow.com/a/47903323/1428034
for i in reversed(range(len(msg._headers))):
header_name = msg._headers[i][0].lower()
if header_name == header.lower():
del msg._headers[i]
def delete_all_headers_except(msg: Message, headers: [str]):
headers = [h.lower() for h in headers]
for i in reversed(range(len(msg._headers))):
header_name = msg._headers[i][0].lower()
if header_name not in headers:
del msg._headers[i]
def email_belongs_to_alias_domains(address: str) -> bool:
"""return True if an email ends with one of the alias domains provided by SimpleLogin"""
for domain in ALIAS_DOMAINS:
if address.endswith("@" + domain):
return True
return False
def email_domain_can_be_used_as_mailbox(email: str) -> bool:
"""return True if an email can be used as a personal email. An email domain can be used if it is not
- one of ALIAS_DOMAINS
- one of custom domains
- disposable domain
"""
domain = get_email_domain_part(email)
if not domain:
return False
if domain in ALIAS_DOMAINS:
return False
from app.models import CustomDomain
if CustomDomain.get_by(domain=domain, verified=True):
LOG.d("domain %s is a SimpleLogin custom domain", domain)
return False
if is_disposable_domain(domain):
LOG.d("Domain %s is disposable", domain)
return False
# check if email MX domain is disposable
mx_domains = get_mx_domain_list(domain)
# if no MX record, email is not valid
if not mx_domains:
LOG.d("No MX record for domain %s", domain)
return False
for mx_domain in mx_domains:
if is_disposable_domain(mx_domain):
LOG.d("MX Domain %s %s is disposable", mx_domain, domain)
return False
return True
def is_disposable_domain(domain):
for d in DISPOSABLE_EMAIL_DOMAINS:
if domain == d:
return True
# subdomain
if domain.endswith("." + d):
return True
return False
def get_mx_domain_list(domain) -> [str]:
"""return list of MX domains for a given email.
domain name ends *without* a dot (".") at the end.
"""
priority_domains = get_mx_domains(domain)
return [d[:-1] for _, d in priority_domains]
def personal_email_already_used(email: str) -> bool:
"""test if an email can be used as user email
"""
if User.get_by(email=email):
return True
return False
def mailbox_already_used(email: str, user) -> bool:
if Mailbox.get_by(email=email, user_id=user.id):
return True
# support the case user wants to re-add their real email as mailbox
# can happen when user changes their root email and wants to add this new email as mailbox
if email == user.email:
return False
return False
def get_orig_message_from_bounce(msg: Message) -> Message:
"""parse the original email from Bounce"""
i = 0
for part in msg.walk():
i += 1
# the original message is the 4th part
# 1st part is the root part, multipart/report
# 2nd is text/plain, Postfix log
# ...
# 7th is original message
if i == 7:
return part
def get_orig_message_from_spamassassin_report(msg: Message) -> Message:
"""parse the original email from Spamassassin report"""
i = 0
for part in msg.walk():
i += 1
# the original message is the 4th part
# 1st part is the root part, multipart/report
# 2nd is text/plain, SpamAssassin part
# 3rd is the original message in message/rfc822 content type
# 4th is original message
if i == 4:
return part
def get_addrs_from_header(msg: Message, header) -> [str]:
"""Get all addresses contained in `header`
Used for To or CC header.
"""
ret = []
header_content = msg.get_all(header)
if not header_content:
return ret
for addrs in header_content:
# force convert header to string, sometimes addrs is Header object
addrs = str(addrs)
for addr in addrs.split(","):
ret.append(addr.strip())
# do not return empty string
return [r for r in ret if r]
def get_spam_info(msg: Message, max_score=None) -> (bool, str):
"""parse SpamAssassin header to detect whether a message is classified as spam.
Return (is spam, spam status detail)
The header format is
```X-Spam-Status: No, score=-0.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
DKIM_VALID_AU,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_PASS,
URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2```
"""
spamassassin_status = msg["X-Spam-Status"]
if not spamassassin_status:
return False, ""
return get_spam_from_header(spamassassin_status, max_score=max_score)
def get_spam_from_header(spam_status_header, max_score=None) -> (bool, str):
"""get spam info from X-Spam-Status header
Return (is spam, spam status detail).
The spam_status_header has the following format
```No, score=-0.1 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
DKIM_VALID_AU,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_MSPIKE_H2,SPF_PASS,
URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.2```
"""
# yes or no
spamassassin_answer = spam_status_header[: spam_status_header.find(",")]
if max_score:
# spam score
# get the score section "score=-0.1"
score_section = (
spam_status_header[spam_status_header.find(",") + 1 :].strip().split(" ")[0]
)
score = float(score_section[len("score=") :])
if score >= max_score:
LOG.warning("Spam score %s exceeds %s", score, max_score)
return True, spam_status_header
return spamassassin_answer.lower() == "yes", spam_status_header
def parseaddr_unicode(addr) -> (str, str):
"""Like parseaddr but return name in unicode instead of in RFC 2047 format
'=?UTF-8?B?TmjGoW4gTmd1eeG7hW4=?= <abcd@gmail.com>' -> ('Nhơn Nguyễn', "abcd@gmail.com")
"""
name, email = parseaddr(addr)
email = email.strip().lower()
if name:
name = name.strip()
decoded_string, charset = decode_header(name)[0]
if charset is not None:
try:
name = decoded_string.decode(charset)
except UnicodeDecodeError:
LOG.warning("Cannot decode addr name %s", name)
name = ""
else:
name = decoded_string
return name, email
def copy(msg: Message) -> Message:
"""return a copy of message"""
return email.message_from_bytes(msg.as_bytes())