> ## Knowledge Base Index
> Fetch the complete knowledge base index at: https://aide.merci-app.com/sitemap.xml
> Use this file to discover available pages before exploring further.
> Pure-Markdown content can be obtained by appending a '.md' suffix to the content URLs listed in the sitemap (without the trailing slash).

# Auto-fill Your Subject Line with Expand


With the **Expand** feature, you can insert text into your emails *and* pre-fill the **Subject** line — all in one go.
No more jumping back and forth between the body and the subject field. **One action, done!**

## Compatibility

Subject line auto-fill works seamlessly with:
* **Gmail**
* **Kiamo**
* **Outlook**
* **Salesforce**
* **Yahoo Mail**

## Adding a Subject Line to a Snippet

Ready to set it up? Here's how:
1. Head over to the **Expand** section in your MerciApp.
2. Create a new snippet or open an existing one.
3. In the **Snippet Content** section, click **`Add a subject`**.
4. A **Subject (optional)** field appears — type in your subject (e.g., *Project Follow-up*).
5. Fill in your **Snippet Name** and **Snippet Trigger**, then save.

Once you insert the snippet into a new email, your subject line fills in automatically. Magic! ✨

To remove the subject from a snippet, just click **Delete subject**.

## Heads Up: Replying in a Thread

When you insert a snippet into a **reply within an existing thread**, the subject line won't auto-fill.
Why? Changing the subject mid-thread would actually break the conversation on the recipient's end — and nobody wants that! So auto-fill stays off in that context.

**Need to change the subject anyway?** Just type it in manually directly in your email client's subject field.

Running into any issues? Don't hesitate to reach out via chat — we're here to help!