---
language:
- en
license: gemma
base_model: google/gemma-3-1b-it
tags:
- text-classification
- email-classification
- fine-tuned
- unsloth
- lora
- qlora
- gemma
- causal-lm
datasets:
- response-classification-dataset
pipeline_tag: text-generation
library_name: transformers
---

# 📧 Customer Email Response Classifier

Fine-tuned **Gemma 3 1B IT** (`google/gemma-3-1b-it`) for classifying customer email responses into 5 categories. The model generates a structured JSON output and is optimized for low-latency deployment via **vLLM**.

## Model Summary

| Property | Value |
|---|---|
| **Base model** | `google/gemma-3-1b-it` |
| **Task** | Generative classification (Causal-LM) |
| **PEFT method** | QLoRA (4-bit) via Unsloth |
| **Training framework** | Unsloth `SFTTrainer` with completion-only masking |
| **Dataset size** | ~3,500 samples |
| **Output format** | `{"classification": "<label>"}` |
| **Deployment target** | vLLM (`/v1/chat/completions`) |

---

## Labels

The model classifies each email into exactly one of:

| Label | Description |
|---|---|
| `automated_reply` | Auto-generated out-of-office or delivery receipts |
| `interested` | Recipient shows genuine interest or engagement |
| `not_interested` | Recipient explicitly declines or opts out |
| `out_of_office` | Human OOO message (distinct from automated replies) |
| `unrelated` | Reply does not relate to the original outreach |

---

## Usage

### Transformers (local)

```python
import json
import torch
from transformers import pipeline

LABELS = ["automated_reply", "interested", "not_interested", "out_of_office", "unrelated"]
SYSTEM_PROMPT = (
    "You are an email-response classifier. "
    f"Classify the email into exactly one of: {', '.join(LABELS)}. "
    'Reply ONLY with a JSON object in the format: {"classification": "<label>"}. '
    "Do not add any explanation."
)

gen = pipeline(
    "text-generation",
    model="OmarioVIC/customer-email-classifier",
    device=0 if torch.cuda.is_available() else -1,
    do_sample=False,
)

def classify(email_text: str) -> str:
    messages = [{"role": "user", "content": f"{SYSTEM_PROMPT}\n\nEmail text:\n{email_text}"}]
    prompt = gen.tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
    output = gen(prompt, max_new_tokens=20)
    generated = output[0]["generated_text"].split("<start_of_turn>model")[-1].strip()
    return json.loads(generated)["classification"]

print(classify("Yeah, Monday works — book a 15-min call."))
# → "interested"
```

### vLLM (recommended for production)

**Serve:**
```bash
pip install vllm

vllm serve OmarioVIC/customer-email-classifier \
    --dtype bfloat16 \
    --max-model-len 512
```

**Query:**
```bash
curl http://localhost:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "OmarioVIC/customer-email-classifier",
    "messages": [{
      "role": "user",
      "content": "Classify into one of: automated_reply, interested, not_interested, out_of_office, unrelated. Reply with JSON only: {\"classification\": \"<label>\"}.\n\nEmail text:\nyeah 15 mins call? free monday"
    }],
    "max_tokens": 20,
    "temperature": 0
  }'
```

---

## Training Details

### Data Format

Each training example is a chat-template conversation:

```json
{
  "messages": [
    {
      "role": "user",
      "content": "<system prompt>\n\nEmail text:\n<raw email body>"
    },
    {
      "role": "assistant",
      "content": "{\"classification\": \"interested\"}"
    }
  ]
}
```

Only the assistant turn is used for loss computation (completion-only masking via `train_on_responses_only`).

### Hyperparameters

| Parameter | Value |
|---|---|
| Epochs | 3 |
| Batch size (per device) | 4 |
| Gradient accumulation steps | 4 |
| Learning rate | 2e-4 |
| LR scheduler | Cosine |
| Warmup steps | 50 |
| Max sequence length | 320 |
| Precision | bfloat16 (Ampere+) / float16 |

### LoRA Config

| Parameter | Value |
|---|---|
| Rank (`r`) | 32 |
| Alpha | 32 |
| Dropout | 0.05 |
| Target modules | All linear layers |
| Gradient checkpointing | Unsloth optimised |

---

## Framework

Training was accelerated using [Unsloth](https://github.com/unslothai/unsloth), which provides:
- **2× faster training** via custom CUDA kernels
- **~60% less VRAM** via QLoRA 4-bit quantisation

The final model was merged to full 16-bit weights (`merged_16bit`) for straightforward vLLM deployment.

---

## Limitations

- Designed for **short email replies** (max 320 tokens including prompt).
- Trained on a specific business outreach dataset; may not generalise to all email domains.
- Output is deterministic (`do_sample=False`, `temperature=0`) — always greedy.

---

## License

This model is derived from `google/gemma-3-1b-it` and is subject to the [Gemma Terms of Use](https://ai.google.dev/gemma/terms).