Gmail agent for job auto-replies

This article describes how I built a privacy-first agent (with Mistral and Ollama) that drafts customized
replies to recruiter emails without sending my inbox to the cloud.

The problem

Like many people job hunting, I get a steady stream of recruiter emails. Many are missing one or more key components: Job ID, pay range (required in California), or complete job description. And they want a quick reply with a resume attached.

I wanted an agent that would:

1. Watch my Gmail inbox for job-related messages
2. Detect whether an email is actually a job description
3. Draft a reply using exact wording I specified
4. Attach my latest resume
5. Run entirely locally for security (no LLM API calls with email content)

My target account: guy.klages@gmail.com

Prerequisites

Before writing an agent, you need to have a clear list of which emails you want to reply to. I used Gmail's built-in Filters to distill which emails to target and then the built-in Labels feature to tag those filtered emails with a "Job" label.

Stack:

• Python 3.12 + Gmail API
• Ollama + Mistral 7B (local)
• Gmail filters for the "Job" label (upstream of the agent)

Important caveats

As you write your prompt, these are good things to keep in mind:

Advice	Description
Output to draft	You will likely need to modify this email agent many times to perfect it, so you don't want this agent to auto-reply until after you've worked out all the kinks.
Structured logging	Log the subject, sender, classification result, and the conditional paragraphs to make debugging reply content easy.

The overall process is:

Gmail Filters route → local LLM classifies → code templates reply → human approves send.

What I asked for (the initial prompt)

I asked Cursor to build an agent to write a customized email reply to any email tagged as "Job" with the following reply rules:

Always start with:

Hi, thank you for your email, I have attached my latest resume.

If the email lacks "Job ID" (subject or body):

To prevent duplicate submission, please tell me the Job ID.

If there's no numeric pay range:

California state law requires Job Descriptions to include the pay range. Please tell me their budgeted W2 pay range for this role.

Always end with:

To answer common questions:

• I'm a US Citizen
• My legal name is Guy Klages
• My birth month and day are 0231
• I don't have any vacations planned
• I just started initial rounds of interviews with three other companies.

Please email me for any other questions or send me the RTR.

Thank you

And one hard constraint: use Mistral locally—no cloud LLM processing email content.

Architecture

The biggest design decision was not letting the LLM write replies.

Task	Tool	Why
"Is this a job description?"	Local Mistral via Ollama	Needs judgment; must stay on-device
Job ID present?	String search	Exact, deterministic
Pay range present?	Regex	Exact, deterministic
Reply body	Python template	Zero wording drift

The following is a flow diagram:

Lesson for builders Use the LLM for classification only. Put legal/compliance/personal boilerplate in code.

---

Project structure

gmail-job-agent/
├── agent.py                         # Main poll loop
├── classifier.py                    # Ollama/Mistral YES-NO classification
├── reply_builder.py                 # Deterministic reply rules
├── gmail_client.py                  # Gmail API: read, draft, label
├── setup_auth.py                    # One-time OAuth
├── config.yaml                      # Account, resume path, mode, labels
├── credentials.json                 # Google OAuth client (gitignored)
├── token.json                       # Refresh token (gitignored)
└── com.guyklages.gmail-agent.plist  # Optional macOS background job

---

Step 1: Google Cloud and Gmail API

Setup

1. Google Cloud Console → new project
2. Enable Gmail API
3. OAuth consent screen → External, Testing mode
4. Credentials → OAuth 2.0 Desktop app
5. Download JSON → save as credentials.json

Scopes needed

gmail.readonly
gmail.send
gmail.modify

Notes:

• gmail.send is required for drafts.
• modify is required for labels.

Error 403: access_denied

After running setup_auth.py, I hit:

Access blocked: Gmail-autoreply-to-job-agent has not completed the Google verification process

Cause: OAuth apps in Testing mode only work for explicitly listed test users.

Fix:

1. APIs & Services → OAuth consent screen
2. Test users → Add guy.klages@gmail.com
3. Save, wait ~1 minute, rerun setup_auth.py

Notes:

• You do not need Google verification for a personal single-user agent.
• Testing mode + your email address as a test user is enough.

---

Step 2: Local Mistral with Ollama

brew install ollama

brew services start ollama

ollama pull mistral

Health check from Python:

requests.get("http://localhost:11434/api/tags")

Mistral ignores YES/NO

Early on, /api/generate returned " Job Opening" instead of YES or NO.

Fix: Switch to the chat API with a strict system prompt, plus fallback parsing:

messages = [
    {
        "role": "system",
        "content": (
            "You classify incoming emails. Respond with exactly one word: "
            "YES if the email is about a job opening or job description, "
            "otherwise NO. Do not explain."
        ),
    },
    {"role": "user", "content": f"Subject: {subject}\n\nBody:\n{body}"},
]

If the model still wanders, parse markers like JOB OPENING, HIRING, NOT A JOB, etc.

Lesson Never assume instruction-following models follow instructions. Always validate and parse defensively.

---

Step 3: OAuth authorization

"I don't have a python directory"

In .venv/bin/ you see:

python -> python3.12
python3 -> python3.12
python3.12 -> /Library/Frameworks/.../python3.12

That's normal. python is a symlink, not a folder.

Run:

cd ~/Projects/gmail-job-agent

.venv/bin/python setup_auth.py

All of .venv/bin/python, python3, and python3.12 work the same.

Success looks like:

Authenticated successfully as guy.klages@gmail.com
Token saved to .../token.json

---

Step 4: Reply rules in code

Pay-range detection uses regex:

PAY_PATTERNS = [
    r'\$[\d,]+(?:\.\d{2})?\s*[-–—to]+\s*\$[\d,]+',
    r'\$[\d,]+k\s*[-–—to]+\s*\$[\d,]+k',
    r'salary[:\s]+\$?[\d,]+',
    # ...
]

Job ID check is a simple case-insensitive search for "job id".

The full reply is assembled from fixed strings.

---

Step 5: Evolving requirements

My first version automatically sent replies and scanned all unread mail. After testing, I changed three things:

Auto-send → drafts

mode: draft  # was: send

Safer default: review every reply before it goes out.

Gmail filter first, agent second

My Gmail filter already applies a Job label. The agent should only process those:

gmail:
  source_label: Job
  processed_label: job-agent/processed

Gmail search query:

label:"Job" -label:job-agent/processed

Flow:

1. Email arrives
2. Gmail filter → Job label
3. Agent polls → classifies → creates draft
4. Agent adds job-agent/processed (won't run twice)

The agent never adds the Job label.

Don't mark messages as read

Originally, mark_processed removed the UNREAD label. I removed that:

body = {"addLabelIds": [self.processed_label_id]}
# No removeLabelIds: ["UNREAD"]

The inbox stays visually "unread" until I actually open the message.

---

Step 6: Running the agent

You can run your agent three ways:

A) One-shot test

.venv/bin/python agent.py --once --verbose

B) Continuous (foreground)

.venv/bin/python agent.py

C) Background (macOS launchd)

cp com.guyklages.gmail-job-agent.plist ~/Library/LaunchAgents/

launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.guyklages.gmail-job-agent.plist

Logs: agent.log in the project directory.

launchctl unload

I tried to restart a service that was never installed:

• Plist wasn't in ~/Library/LaunchAgents/
• Service wasn't loaded

Fix: On modern macOS, use bootstrap / bootout instead of load / unload:

# Install
launchctl bootstrap gui/$(id -u) ~/Library/LaunchAgents/com.guyklages.gmail-job-agent.plist

# Remove
launchctl bootout gui/$(id -u) ~/Library/LaunchAgents/com.guyklages.gmail-job-agent.plist

Note: Error 5 on unload usually means nothing to unload. (not a broken agent)

---

Advice for others building Gmail agents

Start with drafts, not send

Auto-reply agents can embarrass you. Draft mode + human review is the right first ship.

Use Gmail filters as the first gate

Let Gmail's fast, free rules handle obvious routing. Use your agent for judgment calls (classification) and structured output (templated replies).

Keep a processed label

Without the job-agent/processed label, every poll recreates drafts for the same thread. Idempotency matters.

Don't send PII to cloud LLMs

Recruiter emails contain names, companies, sometimes compensation. Local inference (Ollama, llama.cpp, MLX) keeps that on your machine. Gmail API traffic to Google is unavoidable; LLM inference doesn't have to leave your Mac.

Put personal details in config

Legal name, birth month/day, citizenship lines belong in config.yaml (gitignored), not hardcoded in your source repo.

Test classification with real emails

Mistral correctly classified "Backend Engineer opening" vs "Your Amazon order shipped" after the chat API fix, but your recruiter corpus may differ. Keep a --once --verbose loop handy.

OAuth Desktop app, not Web

Web OAuth clients need redirect URI gymnastics. Desktop app + run_local_server() is simpler for CLI agents.

Regex pay-range detection

Regex pay-range detection will miss edge cases such as "$140K DOE" and "€120k", so tune patterns from real emails. When in doubt, include the California pay-range ask since false positives are safer than false negatives.

Resume path: One canonical file

Point config at a single PDF. Update that file when you revise your resume; the agent will then always attach the latest.

---

Reference

Final config file

gmail:
  account: guy.klages@gmail.com
  source_label: Job
  processed_label: job-agent/processed

resume:
  path: /Users/guyklages/Downloads/Guy_Klages_resume.pdf

ollama:
  base_url: http://localhost:11434
  model: mistral

mode: draft

poll_interval_seconds: 300

reply:
  legal_name: Guy Klages
  birth_month_day: "0231"

---

Stop your agent

The methods below turn off everything, depending on how you started your agent.

Running in a terminal

If you ran .venv/bin/python agent.py then go to that terminal window and press CTRL + C. That stops the poll loop immediately.

Running as a backgroup service

If you used launchd to run your agent in the background, check if it's loaded:

launchctl print gui/$(id -u)/com.guyklages.gmail-job-agent

If that prints service info, then stop and remove it by entering:

launchctl bootout gui/$(id -u) ~/Library/LaunchAgents/com.guyklages.gmail-job-agent.plist

(Optional) Remove the plist so it doesn't come back:

rm ~/Library/LaunchAgents/com.guyklages.gmail-job-agent.plist

Kill any leftover agent process

If you're not sure, you can kill any other leftover agent process by entering the following:

pkill -f "gmail-job-agent/agent.py"

You can verify nothing is left with pgrep -fl agent.py. No output means it stopped.

Stop Ollama

Ollama runs in the background and loads Mistral when needed. To stop it, enter:

brew services stop ollama

To prevent it from starting at login, run that command a second time. Then Ollama won't auto-start again until you run brew services start ollama.