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improved helo_hostname for better spam score

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nahakubuilde
2025-06-07 07:36:46 +01:00
parent ae2e5d80f1
commit d0fb2eafd2
5 changed files with 119 additions and 64 deletions
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20
email_server/email_relay.py
View File

@@ -7,6 +7,7 @@ import smtplib
import ssl
from datetime import datetime
from email_server.models import Session, EmailLog
from email_server.settings_loader import load_settings
from email_server.tool_box import get_logger
logger = get_logger()
@@ -16,6 +17,11 @@ class EmailRelay:
def __init__(self):
self.timeout = 30 # Increased timeout for TLS negotiations
# Get the configured hostname for HELO/EHLO identification
settings = load_settings()
self.hostname = settings['Server'].get('helo_hostname',
settings['Server'].get('hostname', 'localhost'))
logger.debug(f"EmailRelay initialized with hostname: {self.hostname}")
def relay_email(self, mail_from, rcpt_tos, content):
"""Relay email to recipient's mail server with opportunistic TLS."""
@@ -53,8 +59,9 @@ class EmailRelay:
# Try to enable TLS if the server supports it
try:
# Check if server supports STARTTLS
relay_server.ehlo()
# Check if server supports STARTTLS - use proper hostname for EHLO
logger.debug(f'Sending EHLO {self.hostname} to {mx_host}')
relay_server.ehlo(self.hostname)
if relay_server.has_extn('starttls'):
logger.debug(f'Starting TLS connection to {mx_host}')
context = ssl.create_default_context()
@@ -62,7 +69,8 @@ class EmailRelay:
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE
relay_server.starttls(context=context)
relay_server.ehlo() # Say hello again after STARTTLS
logger.debug(f'Sending EHLO {self.hostname} again after STARTTLS to {mx_host}')
relay_server.ehlo(self.hostname) # Say hello again after STARTTLS with proper hostname
logger.debug(f'TLS connection established to {mx_host}')
else:
logger.warning(f'Server {mx_host} does not support STARTTLS, using plain text')
@@ -94,13 +102,15 @@ class EmailRelay:
# Try TLS with backup server too
try:
backup_server.ehlo()
logger.debug(f'Sending EHLO {self.hostname} to backup {backup_mx}')
backup_server.ehlo(self.hostname)
if backup_server.has_extn('starttls'):
context = ssl.create_default_context()
context.check_hostname = False
context.verify_mode = ssl.CERT_NONE
backup_server.starttls(context=context)
backup_server.ehlo()
logger.debug(f'Sending EHLO {self.hostname} again after STARTTLS to backup {backup_mx}')
backup_server.ehlo(self.hostname)
logger.debug(f'TLS connection established to backup {backup_mx}')
except Exception:
logger.warning(f'STARTTLS failed with backup {backup_mx}, using plain text')

30
email_server/server_runner.py
View File

@@ -9,7 +9,7 @@ from email_server.tool_box import get_logger
# Import our modules
from email_server.models import create_tables
from email_server.smtp_handler import EnhancedCustomSMTPHandler, PlainController
from email_server.smtp_handler import EnhancedCustomSMTPHandler, PlainController, TLSController
from email_server.tls_utils import generate_self_signed_cert, create_ssl_context
from email_server.dkim_manager import DKIMManager
from aiosmtpd.controller import Controller
@@ -18,7 +18,7 @@ from aiosmtpd.smtp import SMTP as AIOSMTP
settings = load_settings()
SMTP_PORT = int(settings['Server']['SMTP_PORT'])
SMTP_TLS_PORT = int(settings['Server']['SMTP_TLS_PORT'])
HOSTNAME = settings['Server']['HOSTNAME']
HOSTNAME = settings['Server'].get('helo_hostname', settings['Server'].get('hostname', 'localhost'))
LOG_LEVEL = settings['Logging']['LOG_LEVEL']
BIND_IP = settings['Server']['BIND_IP']
@@ -94,37 +94,25 @@ async def start_server():
logger.error("Failed to create SSL context")
return
logger.debug(f"SSL context created: {ssl_context}")
logger.debug(f"SSL context type: {type(ssl_context)}")
# Start plain SMTP server (with IP whitelist fallback)
handler_plain = EnhancedCustomSMTPHandler()
controller_plain = PlainController(
handler_plain,
hostname=BIND_IP,
server_hostname="TestEnvironment",
hostname=HOSTNAME, # Use proper hostname for HELO identification
port=SMTP_PORT
)
controller_plain.start()
logger.debug(f'Starting plain SMTP server on {HOSTNAME}:{SMTP_PORT}...')
# Start TLS SMTP server using closure pattern like the original
# Start TLS SMTP server using the updated TLSController
handler_tls = EnhancedCustomSMTPHandler()
# Define TLS controller class with ssl_context in closure (like original)
class TLSController(Controller):
def factory(self):
return AIOSMTP(
self.handler,
tls_context=ssl_context, # Use ssl_context from closure
require_starttls=False, # Don't force STARTTLS, but make it available
auth_require_tls=True, # If auth is used, require TLS
authenticator=self.handler.combined_authenticator,
decode_data=True,
hostname=self.hostname
)
controller_tls = TLSController(
handler_tls,
hostname=BIND_IP,
server_hostname="TestEnvironment",
ssl_context=ssl_context,
hostname=HOSTNAME, # Use proper hostname for HELO identification
port=SMTP_TLS_PORT
)
controller_tls.start()

3
email_server/settings_loader.py
View File

@@ -13,7 +13,8 @@ DEFAULTS = {
'Server': {
'SMTP_PORT': '4025',
'SMTP_TLS_PORT': '40587',
'HOSTNAME': 'localhost',
'HOSTNAME': 'mail.example.com',
'helo_hostname': 'mail.example.com',
'BIND_IP': '0.0.0.0',
},
'Database': {

0
email_server/smtp_config.py Normal file
View File

130
email_server/smtp_handler.py
View File

@@ -63,6 +63,9 @@ class EnhancedCustomSMTPHandler:
def _ensure_required_headers(self, content: str, envelope, message_id: str, custom_headers: list = None) -> str:
"""Ensure all required email headers are present and properly formatted.
Following RFC 5322 header order and best practices for spam score reduction.
Optimized based on Gmail's header structure for better deliverability.
Args:
content (str): Email content.
envelope: SMTP envelope.
@@ -73,8 +76,12 @@ class EnhancedCustomSMTPHandler:
str: Email content with all required headers properly formatted.
"""
import email.utils
from email_server.settings_loader import load_settings
try:
settings = load_settings()
server_hostname = settings.get('Server', 'helo_hostname', fallback='mail.netbro.uk')
logger.debug(f"Processing headers for message {message_id}")
# Parse the message properly
@@ -87,6 +94,7 @@ class EnhancedCustomSMTPHandler:
# Find header/body boundary and collect existing headers
body_start = 0
existing_headers = {}
original_header_order = []
for i, line in enumerate(lines):
if line.strip() == '':
@@ -104,81 +112,106 @@ class EnhancedCustomSMTPHandler:
j += 1
existing_headers[header_name_lower] = header_value
original_header_order.append((header_name.strip(), header_value))
logger.debug(f"Found existing header: {header_name_lower} = {header_value}")
# Extract body
# Extract body and clean it
body_lines = lines[body_start:] if body_start < len(lines) else []
while body_lines and body_lines[-1].strip() == '':
body_lines.pop()
body = '\n'.join(body_lines)
# Build required headers list
# Build headers in optimized order based on Gmail's structure
required_headers = []
# Add custom headers first
if custom_headers:
for header_name, header_value in custom_headers:
required_headers.append(f"{header_name}: {header_value}")
logger.debug(f"Added custom header: {header_name}: {header_value}")
# Message-ID (always add to ensure it's present)
# 1. Message-ID (critical for spam filters)
if 'message-id' in existing_headers:
required_headers.append(f"Message-ID: {existing_headers['message-id']}")
else:
domain = envelope.mail_from.split('@')[1] if '@' in envelope.mail_from else 'localhost'
domain = envelope.mail_from.split('@')[1] if '@' in envelope.mail_from else server_hostname.replace('mail.', '')
required_headers.append(f"Message-ID: <{message_id}@{domain}>")
# Date
# 2. Date (critical for spam filters)
if 'date' in existing_headers:
required_headers.append(f"Date: {existing_headers['date']}")
else:
date_str = email.utils.formatdate(localtime=True)
required_headers.append(f"Date: {date_str}")
# From (required)
if 'from' in existing_headers:
required_headers.append(f"From: {existing_headers['from']}")
# 3. MIME-Version (declare MIME compliance early)
if 'mime-version' in existing_headers:
required_headers.append(f"MIME-Version: {existing_headers['mime-version']}")
else:
required_headers.append(f"From: {envelope.mail_from}")
required_headers.append("MIME-Version: 1.0")
# To (required)
# 4. User-Agent (if present, helps with reputation)
if 'user-agent' in existing_headers:
required_headers.append(f"User-Agent: {existing_headers['user-agent']}")
# 5. Content-Language (if present)
if 'content-language' in existing_headers:
required_headers.append(f"Content-Language: {existing_headers['content-language']}")
# 6. To (primary recipients - critical)
if 'to' in existing_headers:
required_headers.append(f"To: {existing_headers['to']}")
else:
to_list = ', '.join(envelope.rcpt_tos)
required_headers.append(f"To: {to_list}")
# Subject (preserve existing or add empty)
# 7. From (sender identification - critical)
if 'from' in existing_headers:
required_headers.append(f"From: {existing_headers['from']}")
else:
required_headers.append(f"From: {envelope.mail_from}")
# 8. Subject (message topic - critical)
if 'subject' in existing_headers:
required_headers.append(f"Subject: {existing_headers['subject']}")
else:
required_headers.append("Subject: ")
# MIME headers
if 'mime-version' in existing_headers:
required_headers.append(f"MIME-Version: {existing_headers['mime-version']}")
else:
required_headers.append("MIME-Version: 1.0")
# 9. Content-Type (media type information)
if 'content-type' in existing_headers:
required_headers.append(f"Content-Type: {existing_headers['content-type']}")
else:
required_headers.append("Content-Type: text/plain; charset=utf-8")
required_headers.append("Content-Type: text/plain; charset=UTF-8; format=flowed")
# 10. Content-Transfer-Encoding
if 'content-transfer-encoding' in existing_headers:
required_headers.append(f"Content-Transfer-Encoding: {existing_headers['content-transfer-encoding']}")
else:
required_headers.append("Content-Transfer-Encoding: 7bit")
# Add any other existing headers
# Add custom headers after essential headers but before misc headers
if custom_headers:
for header_name, header_value in custom_headers:
# Skip if already added in essential headers
if header_name.lower() not in ['message-id', 'date', 'mime-version', 'user-agent',
'content-language', 'to', 'from', 'subject',
'content-type', 'content-transfer-encoding']:
required_headers.append(f"{header_name}: {header_value}")
logger.debug(f"Added custom header: {header_name}: {header_value}")
# Add any other existing headers that weren't handled above
essential_headers = {
'message-id', 'date', 'from', 'to', 'subject',
'mime-version', 'content-type', 'content-transfer-encoding'
'mime-version', 'content-type', 'content-transfer-encoding',
'user-agent', 'content-language'
}
for header_name, header_value in existing_headers.items():
if header_name not in essential_headers:
required_headers.append(f"{header_name.title()}: {header_value}")
# Preserve original header names and values for non-essential headers
for header_name, header_value in original_header_order:
if header_name.lower() not in essential_headers:
# Skip custom headers we already added
skip = False
if custom_headers:
for custom_name, _ in custom_headers:
if header_name.lower() == custom_name.lower():
skip = True
break
if not skip:
required_headers.append(f"{header_name}: {header_value}")
# Build final message
final_content = '\r\n'.join(required_headers)
@@ -201,7 +234,7 @@ class EnhancedCustomSMTPHandler:
return content
async def handle_DATA(self, server, session, envelope):
"""Handle incoming email data."""
"""Handle incoming email data with improved header management."""
try:
message_id = str(uuid.uuid4())
logger.debug(f'Received email {message_id} from {envelope.mail_from} to {envelope.rcpt_tos}')
@@ -220,6 +253,18 @@ class EnhancedCustomSMTPHandler:
if sender_domain:
custom_headers = self.dkim_manager.get_active_custom_headers(sender_domain)
# Add beneficial headers for spam score improvement
client_ip = getattr(session, 'peer', ['unknown'])[0] if hasattr(session, 'peer') else None
if client_ip:
# Add X-Originating-IP header (helps with reputation)
custom_headers.append(('X-Originating-IP', f'[{client_ip}]'))
# Add X-Mailer header for identification
custom_headers.append(('X-Mailer', 'NetBro Mail Server 1.0'))
# Add X-Priority header (normal priority)
custom_headers.append(('X-Priority', '3'))
# Ensure required headers are present (including custom headers)
content = self._ensure_required_headers(content, envelope, message_id, custom_headers)
@@ -294,28 +339,39 @@ class TLSController(Controller):
"""Custom controller with TLS support - modeled after the working original."""
def __init__(self, handler, ssl_context, hostname='localhost', port=40587):
self.ssl_context = ssl_context
super().__init__(handler, hostname=hostname, port=port)
logger.debug(f"TLSController __init__: ssl_context={ssl_context is not None}")
self._ssl_context = ssl_context # Use private attribute to avoid conflicts
self.smtp_hostname = hostname # Store for HELO identification
super().__init__(handler, hostname='0.0.0.0', port=port) # Bind to all interfaces
def factory(self):
return AIOSMTP(
logger.debug(f"TLSController factory: ssl_context={self._ssl_context is not None}")
logger.debug(f"TLSController factory: ssl_context object={self._ssl_context}")
logger.debug(f"TLSController factory: hostname={self.smtp_hostname}")
smtp_instance = AIOSMTP(
self.handler,
tls_context=self.ssl_context,
require_starttls=True, # Don't force STARTTLS, but make it available
tls_context=self._ssl_context,
require_starttls=False, # Don't require STARTTLS immediately, but make it available
auth_require_tls=True, # If auth is used, require TLS
authenticator=self.handler.combined_authenticator,
decode_data=True,
hostname=self.hostname
hostname=self.smtp_hostname # Use proper hostname for HELO
)
logger.debug(f"TLSController AIOSMTP instance created with TLS: {hasattr(smtp_instance, 'tls_context')}")
return smtp_instance
class PlainController(Controller):
"""Controller for plain SMTP with username/password and IP-based authentication."""
def __init__(self, handler, hostname='localhost', port=4025):
self.smtp_hostname = hostname # Store for HELO identification
super().__init__(handler, hostname='0.0.0.0', port=port) # Bind to all interfaces
def factory(self):
return AIOSMTP(
self.handler,
authenticator=self.handler.combined_authenticator,
auth_require_tls=False, # Allow AUTH over plain text (not recommended for production)
decode_data=True,
hostname=self.hostname
hostname=self.smtp_hostname # Use proper hostname for HELO
)