from __future__ import annotations import base64 import email import json import os import time import uuid from concurrent.futures import ThreadPoolExecutor from email.message import Message from functools import wraps from smtplib import SMTP, SMTPException from typing import Optional, Dict, List, Callable import newrelic.agent from attr import dataclass from app import config from app.email import headers from app.log import LOG from app.message_utils import message_to_bytes, message_format_base64_parts @dataclass class SendRequest: SAVE_EXTENSION = "sendrequest" envelope_from: str envelope_to: str msg: Message mail_options: Dict = {} rcpt_options: Dict = {} is_forward: bool = False ignore_smtp_errors: bool = False def to_bytes(self) -> bytes: if not config.SAVE_UNSENT_DIR: LOG.d("Skipping saving unsent message because SAVE_UNSENT_DIR is not set") return serialized_message = message_to_bytes(self.msg) data = { "envelope_from": self.envelope_from, "envelope_to": self.envelope_to, "msg": base64.b64encode(serialized_message).decode("utf-8"), "mail_options": self.mail_options, "rcpt_options": self.rcpt_options, "is_forward": self.is_forward, } return json.dumps(data).encode("utf-8") @staticmethod def load_from_file(file_path: str) -> SendRequest: with open(file_path, "rb") as fd: return SendRequest.load_from_bytes(fd.read()) @staticmethod def load_from_bytes(data: bytes) -> SendRequest: decoded_data = json.loads(data) msg_data = base64.b64decode(decoded_data["msg"]) msg = email.message_from_bytes(msg_data) return SendRequest( envelope_from=decoded_data["envelope_from"], envelope_to=decoded_data["envelope_to"], msg=msg, mail_options=decoded_data["mail_options"], rcpt_options=decoded_data["rcpt_options"], is_forward=decoded_data["is_forward"], ) class MailSender: def __init__(self): self._pool: Optional[ThreadPoolExecutor] = None self._store_emails = False self._emails_sent: List[SendRequest] = [] def store_emails_instead_of_sending(self, store_emails: bool = True): self._store_emails = store_emails def purge_stored_emails(self): self._emails_sent = [] def get_stored_emails(self) -> List[SendRequest]: return self._emails_sent def store_emails_test_decorator(self, fn: Callable) -> Callable: @wraps(fn) def wrapper(*args, **kwargs): self.purge_stored_emails() self.store_emails_instead_of_sending() result = fn(*args, **kwargs) self.purge_stored_emails() self.store_emails_instead_of_sending(False) return result return wrapper def enable_background_pool(self, max_workers=10): self._pool = ThreadPoolExecutor(max_workers=max_workers) def send(self, send_request: SendRequest, retries: int = 2) -> bool: """replace smtp.sendmail""" if self._store_emails: self._emails_sent.append(send_request) if config.NOT_SEND_EMAIL: LOG.d( "send email with subject '%s', from '%s' to '%s'", send_request.msg[headers.SUBJECT], send_request.msg[headers.FROM], send_request.msg[headers.TO], ) return True if not self._pool: return self._send_to_smtp(send_request, retries) else: self._pool.submit(self._send_to_smtp, (send_request, retries)) return True def _send_to_smtp(self, send_request: SendRequest, retries: int) -> bool: try: start = time.time() with SMTP( config.POSTFIX_SERVER, config.POSTFIX_PORT, timeout=config.POSTFIX_TIMEOUT, ) as smtp: if config.POSTFIX_SUBMISSION_TLS: smtp.starttls() elapsed = time.time() - start LOG.d("getting a smtp connection takes seconds %s", elapsed) newrelic.agent.record_custom_metric( "Custom/smtp_connection_time", elapsed ) # smtp.send_message has UnicodeEncodeError # encode message raw directly instead LOG.d( "Sendmail mail_from:%s, rcpt_to:%s, header_from:%s, header_to:%s, header_cc:%s", send_request.envelope_from, send_request.envelope_to, send_request.msg[headers.FROM], send_request.msg[headers.TO], send_request.msg[headers.CC], ) smtp.sendmail( send_request.envelope_from, send_request.envelope_to, message_to_bytes(send_request.msg), send_request.mail_options, send_request.rcpt_options, ) newrelic.agent.record_custom_metric( "Custom/smtp_sending_time", time.time() - start ) return True except ( SMTPException, ConnectionRefusedError, TimeoutError, ) as e: if retries > 0: time.sleep(0.3 * retries) return self._send_to_smtp(send_request, retries - 1) else: if send_request.ignore_smtp_errors: LOG.e(f"Ignore smtp error {e}") return False LOG.e( f"Could not send message to smtp server {config.POSTFIX_SERVER}:{config.POSTFIX_PORT}" ) if config.SAVE_UNSENT_DIR: self._save_request_to_unsent_dir(send_request) return False def _save_request_to_unsent_dir( self, send_request: SendRequest, prefix: str = "DeliveryFail" ): file_name = ( f"{prefix}-{int(time.time())}-{uuid.uuid4()}.{SendRequest.SAVE_EXTENSION}" ) file_path = os.path.join(config.SAVE_UNSENT_DIR, file_name) file_contents = send_request.to_bytes() with open(file_path, "wb") as fd: fd.write(file_contents) LOG.i(f"Saved unsent message {file_path}") mail_sender = MailSender() def save_request_to_failed_dir(exception_name: str, send_request: SendRequest): file_name = f"{exception_name}-{int(time.time())}-{uuid.uuid4()}.{SendRequest.SAVE_EXTENSION}" failed_file_dir = os.path.join(config.SAVE_UNSENT_DIR, "failed") try: os.makedirs(failed_file_dir) except FileExistsError: pass file_path = os.path.join(failed_file_dir, file_name) file_contents = send_request.to_bytes() with open(file_path, "wb") as fd: fd.write(file_contents) return file_path def load_unsent_mails_from_fs_and_resend(): if not config.SAVE_UNSENT_DIR: return for filename in os.listdir(config.SAVE_UNSENT_DIR): (_, extension) = os.path.splitext(filename) if extension[1:] != SendRequest.SAVE_EXTENSION: LOG.i(f"Skipping {filename} does not have the proper extension") continue full_file_path = os.path.join(config.SAVE_UNSENT_DIR, filename) if not os.path.isfile(full_file_path): LOG.i(f"Skipping {filename} as it's not a file") continue LOG.i(f"Trying to re-deliver email {filename}") try: send_request = SendRequest.load_from_file(full_file_path) except Exception as e: LOG.e(f"Cannot load {filename}. Error {e}") continue try: send_request.ignore_smtp_errors = True if mail_sender.send(send_request, 2): os.unlink(full_file_path) newrelic.agent.record_custom_event( "DeliverUnsentEmail", {"delivered": "true"} ) else: newrelic.agent.record_custom_event( "DeliverUnsentEmail", {"delivered": "false"} ) except Exception as e: # Unlink original file to avoid re-doing the same os.unlink(full_file_path) LOG.e( "email sending failed with error:%s " "envelope %s -> %s, mail %s -> %s saved to %s", e, send_request.envelope_from, send_request.envelope_to, send_request.msg[headers.FROM], send_request.msg[headers.TO], save_request_to_failed_dir(e.__class__.__name__, send_request), ) def sl_sendmail( envelope_from: str, envelope_to: str, msg: Message, mail_options=(), rcpt_options=(), is_forward: bool = False, retries=2, ignore_smtp_error=False, ): send_request = SendRequest( envelope_from, envelope_to, message_format_base64_parts(msg), mail_options, rcpt_options, is_forward, ignore_smtp_error, ) mail_sender.send(send_request, retries)