Mailpilot Agent

MailPilot Agent

Crash-safe mail merge for AI agents. Send a batch of personalized emails from a spreadsheet and track whether each one was sent and delivered. Two modes:

• Simple mode — one recipient list + one template → the same email to everyone (with a personalized greeting).
• Grouped mode — the list has a group column → each group gets its own template.

Core principles (important)

• The tool only faithfully sends the list you already grouped. It does not decide who belongs in which group. Deciding the grouping is the user's job (optionally with the agent's help in chat).
• Rows with no valid email, or whose template can't be found, are surfaced for review and are NEVER sent automatically.
• Sending is idempotent and crash-safe: send writes an append-only JSONL checkpoint after each SMTP result, then atomically syncs the CSV. Re-run after an interruption and it only sends what's left; rows marked "sent" in the list are skipped.
• send marking a row sent only means "the mail server accepted it" — NOT that it was delivered. Always run bounces afterward to reconcile.

Workflow the agent should follow

1. Self-check first: run doctor to verify deps / config / SMTP. Fix what it flags — including that obtaining the email app password is a step the user must do themselves in their mail provider's settings (the agent can't log into their webmail / pass 2FA). Guide them using references/email_provider_setup.md, then write it into config.yaml.
2. Preview: user provides the list → run preview → read the per-group counts + one sample per group + the flagged un-sendable rows out loud in the chat for the user to review (do NOT email a report).
3. Wait for confirmation: only proceed after the user says "send" (they may give a time). Send nothing before that.
4. Test first: send --redirect-to --limit 3 so they see the real emails.
5. Send for real: send (optionally --at to schedule, --sleep to throttle, --only per group). Report success/failure counts back.
6. Reconcile bounces: run bounces to mark undelivered rows bounced, and report that list to the user (those need manual follow-up).

Command reference

Prereq: copy config.example.yaml to config.yaml and fill in your app password (NOT your login password — see references/email_provider_setup.md).

pip install pandas openpyxl jinja2 pyyaml certifi          # first-time deps

python scripts/mailer.py doctor --config config.yaml        # check deps / config / SMTP

# Preview (review in chat). Simple mode picks a template; grouped mode auto-detects the group column.
python scripts/mailer.py preview list.xlsx --template default --out sendable.csv
python scripts/mailer.py preview list.xlsx --out sendable.csv        # auto-groups if a group column exists
python scripts/mailer.py preview samples/messy_registrations.csv --out sendable.csv    # safety demo

# Test send (redirect everything to a test inbox, a few at a time)
python scripts/mailer.py send --input sendable.csv --config config.yaml --redirect-to test@example.com --limit 3

# Real send (idempotent; schedule / throttle / send one group)
python scripts/mailer.py send --input sendable.csv --config config.yaml
#   checkpoint ledger defaults to sendable.csv.sendlog.jsonl
#   --at "2026-07-02 09:00"   send at a scheduled time (process must stay running)
#   --sleep 2                 pause 2s between emails (throttle for large batches)
#   --only confirmed          send only one template/group

# Reconcile bounces after sending
python scripts/mailer.py bounces --input sendable.csv --config config.yaml            # preview
python scripts/mailer.py bounces --input sendable.csv --config config.yaml --apply     # mark bounced rows

If installed with python -m pip install -e ., the same commands are available via mailpilot:

mailpilot preview list.xlsx --out sendable.csv
mailpilot send --input sendable.csv --config config.yaml --dry-run

List format

Needs at least an email column (headers containing "email"/"邮箱" are auto-detected). Optional:

• name column — for the personalized greeting {{ name }};
• group column (headers containing "group"/"type"/"组别" etc.) — presence switches on grouped mode; the value = which template to use;
• sent column (headers containing "sent"/"已发") — rows with a truthy value (yes/1/是/sent) are skipped, so you don't re-send ones already sent manually.

Templates

Plain text + Jinja2 variables, in templates/:

• Simple mode uses templates/default.txt (override with --template ).
• Grouped mode: group value confirmed → templates/confirmed.txt, and so on.
• The first line Subject: ... is the subject; the rest is the body. {{ name }} is replaced with the recipient's name.

Steps only the user can do (agent: give guidance, then wait)

1. Get the mail app password / authorization code — requires logging into the provider and passing 2FA; the agent can't do this. Guide the user per references/email_provider_setup.md, then put it in config.yaml.
2. Provide the real list and email content.
3. Confirm sending — for outbound bulk mail, the final go/no-go and timing are the user's call.

Config & docs

• config.example.yaml — SMTP config template (copy to config.yaml). Includes unsubscribe (adds a List-Unsubscribe header to improve bulk deliverability) and optional imap (for bounces).
• references/email_provider_setup.md — how to get an app password for Gmail / Outlook / NetEase, plus deliverability notes.
• samples/ — event_registrations.csv (grouped mode: confirmed / waitlist), attendees.csv (simple mode), and messy_registrations.csv (safety demo for invalid emails, missing templates, and already-sent rows).

Known limits

• Must run on a local-execution AI (Claude Code / Cowork / Codex CLI / Hermes). Plain web chat sandboxes can't reach mail servers, so they can't actually send.
• Deliverability: sending bulk to external/foreign inboxes from an ordinary mailbox may hit spam or rate limits. For one-off blasts of ~1000+, a transactional email service (Amazon SES / SendGrid / Mailgun / Aliyun DirectMail) delivers more reliably — switching only changes config.yaml. Always run bounces afterward.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: KayZhongyi
• Source: KayZhongyi/mailpilot-agent
• License: MIT

Install and usage instructions live in the source repository linked above.