290 lines
9.7 KiB
Python
290 lines
9.7 KiB
Python
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"""IMAP / SMTP email channel adapter.
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Handles:
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- Polling the inbox for unread messages (IMAP)
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- Thread tracking via Message-ID / In-Reply-To / References headers
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- Sending reply emails (SMTP) with proper threading headers
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- Stripping quoted reply text so the agent only sees the new content
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"""
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import email
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import email.header
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import email.utils
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import imaplib
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import logging
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import re
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import smtplib
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import time
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from email.mime.multipart import MIMEMultipart
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from email.mime.text import MIMEText
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from typing import Optional
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logger = logging.getLogger(__name__)
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# ---------------------------------------------------------------------------
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# Helpers
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# ---------------------------------------------------------------------------
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def _decode_header(value: str) -> str:
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"""Decode an RFC-2047 encoded email header value."""
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parts = email.header.decode_header(value or "")
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decoded = []
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for part, charset in parts:
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if isinstance(part, bytes):
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decoded.append(part.decode(charset or "utf-8", errors="replace"))
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else:
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decoded.append(part)
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return "".join(decoded)
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def _extract_text(msg: email.message.Message) -> str:
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"""Extract the plain-text body from a (potentially multi-part) message."""
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if msg.is_multipart():
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for part in msg.walk():
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if (
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part.get_content_type() == "text/plain"
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and "attachment" not in str(part.get("Content-Disposition", ""))
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):
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charset = part.get_content_charset() or "utf-8"
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payload = part.get_payload(decode=True)
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if payload:
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return payload.decode(charset, errors="replace")
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else:
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charset = msg.get_content_charset() or "utf-8"
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payload = msg.get_payload(decode=True)
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if payload:
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return payload.decode(charset, errors="replace")
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return ""
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def _strip_quoted_text(text: str) -> str:
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"""Remove quoted reply text from the email body.
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Heuristics:
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- Drop lines starting with ">"
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- Stop at common reply-separator patterns
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"""
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lines = text.splitlines()
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result: list[str] = []
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for line in lines:
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stripped = line.strip()
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if stripped.startswith(">"):
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continue
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# Common separators used by email clients
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if re.match(r"^-{3,}|^_{3,}|^={3,}", stripped):
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break
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if re.match(r"^On .+ wrote:$", stripped):
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break
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if re.match(r"^Am .+ schrieb .+:$", stripped): # German Outlook/Thunderbird
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break
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if "-----Original Message-----" in stripped:
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break
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result.append(line)
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return "\n".join(result).strip()
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def _generate_message_id(from_addr: str) -> str:
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domain = from_addr.split("@")[-1] if "@" in from_addr else "meister-eder.local"
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return f"<{time.time():.6f}.{id(from_addr)}@{domain}>"
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# ---------------------------------------------------------------------------
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# Main class
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# ---------------------------------------------------------------------------
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class EmailChannel:
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"""Wraps IMAP polling and SMTP sending for the email conversation channel."""
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def __init__(
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self,
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imap_host: str,
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imap_port: int,
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smtp_host: str,
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smtp_port: int,
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username: str,
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password: str,
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use_ssl: bool = True,
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use_tls: bool = True,
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registration_email: str = "",
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) -> None:
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self._imap_host = imap_host
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self._imap_port = imap_port
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self._smtp_host = smtp_host
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self._smtp_port = smtp_port
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self._username = username
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self._password = password
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self._use_ssl = use_ssl
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self._use_tls = use_tls
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self._from_email = registration_email or username
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# ------------------------------------------------------------------
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# IMAP — receive
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# ------------------------------------------------------------------
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def fetch_unread_messages(self) -> list[dict]:
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"""Poll the inbox and return all unread messages as structured dicts.
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Each dict contains:
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from — sender email address
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subject — decoded subject line
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message_id — Message-ID header of this email
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in_reply_to — In-Reply-To header (may be empty)
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references — References header (may be empty)
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thread_id — canonical ID for the email thread
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body — stripped plain-text body (quoted text removed)
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"""
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messages: list[dict] = []
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try:
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imap = self._connect_imap()
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imap.select("INBOX")
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_, data = imap.search(None, "UNSEEN")
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msg_nums = data[0].split()
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for num in msg_nums:
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try:
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_, raw_data = imap.fetch(num, "(RFC822)")
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raw = raw_data[0][1]
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msg = email.message_from_bytes(raw)
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from_addr = email.utils.parseaddr(msg.get("From", ""))[1]
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subject = _decode_header(msg.get("Subject", "(no subject)"))
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message_id = msg.get("Message-ID", "").strip()
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in_reply_to = msg.get("In-Reply-To", "").strip()
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references = msg.get("References", "").strip()
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body = _extract_text(msg)
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body = _strip_quoted_text(body)
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if not body.strip():
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imap.store(num, "+FLAGS", "\\Seen")
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continue
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thread_id = self._resolve_thread_id(message_id, in_reply_to, references)
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messages.append(
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{
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"from": from_addr,
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"subject": subject,
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"message_id": message_id,
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"in_reply_to": in_reply_to,
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"references": references,
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"thread_id": thread_id,
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"body": body,
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}
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)
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imap.store(num, "+FLAGS", "\\Seen")
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except Exception:
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logger.exception("Error processing IMAP message %s", num)
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imap.logout()
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except Exception:
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logger.exception("IMAP connection/fetch error")
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return messages
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# ------------------------------------------------------------------
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# SMTP — send
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# ------------------------------------------------------------------
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def send_reply(
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self,
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to: str,
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subject: str,
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body: str,
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in_reply_to: str = "",
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references: str = "",
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) -> str:
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"""Send an email reply.
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Returns the new Message-ID so the caller can track the thread.
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"""
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new_message_id = _generate_message_id(self._from_email)
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# Ensure subject starts with "Re:"
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if not subject.lower().startswith("re:"):
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subject = f"Re: {subject}"
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# Build References chain
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ref_parts = [r for r in [references, in_reply_to] if r]
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new_references = " ".join(ref_parts)
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msg = MIMEMultipart("alternative")
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msg["From"] = self._from_email
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msg["To"] = to
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msg["Subject"] = subject
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msg["Message-ID"] = new_message_id
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if in_reply_to:
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msg["In-Reply-To"] = in_reply_to
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if new_references:
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msg["References"] = new_references
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msg.attach(MIMEText(body, "plain", "utf-8"))
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if not self._smtp_host:
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logger.warning("SMTP not configured — reply NOT sent to %s: %s", to, subject)
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logger.debug("Reply body:\n%s", body)
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return new_message_id
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try:
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if self._use_tls:
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server = smtplib.SMTP(self._smtp_host, self._smtp_port)
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server.starttls()
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else:
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server = smtplib.SMTP_SSL(self._smtp_host, self._smtp_port)
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server.login(self._username, self._password)
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server.sendmail(self._from_email, [to], msg.as_string())
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server.quit()
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logger.info("Reply sent to %s (thread %s)", to, in_reply_to or new_message_id)
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except Exception:
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logger.exception("Failed to send reply to %s", to)
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return new_message_id
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def send_reminder(
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self,
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to: str,
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subject: str,
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body: str,
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in_reply_to: str = "",
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references: str = "",
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) -> None:
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"""Send a reminder email for an incomplete registration."""
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self.send_reply(
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to=to,
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subject=subject,
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body=body,
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in_reply_to=in_reply_to,
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references=references,
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)
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# ------------------------------------------------------------------
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# Internal helpers
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# ------------------------------------------------------------------
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def _connect_imap(self) -> imaplib.IMAP4:
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if self._use_ssl:
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conn = imaplib.IMAP4_SSL(self._imap_host, self._imap_port)
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else:
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conn = imaplib.IMAP4(self._imap_host, self._imap_port)
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conn.login(self._username, self._password)
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return conn
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@staticmethod
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def _resolve_thread_id(message_id: str, in_reply_to: str, references: str) -> str:
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"""Determine the canonical thread ID from email threading headers.
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The root of the thread is the first message ever sent — its ID is the
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first token in the References header (oldest first convention).
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"""
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if references:
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first_ref = references.strip().split()[0]
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return first_ref
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if in_reply_to:
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return in_reply_to.strip()
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return message_id.strip() or f"<unknown-{time.time():.0f}>"
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