Reply-To Address

Configure a Reply-To address so that when recipients hit reply on any email sent from your workspace, their mail client routes the reply directly to the address you specify: Gmail, Outlook, or any other inbox.

How Reply-To is applied depends on send type:

API sends: opt-in per request. Pass "reply_to": true in the request body. If omitted (default false), no Reply-To header is injected even if a workspace address is configured.
Campaigns: a Reply-To field appears in Step 1 of campaign creation, prefilled from the workspace setting. You can override it per campaign or leave it blank to use the workspace default.

No DNS records, SES receipt rules, or inbox forwarding rules are required.

How It Works

When Reply-To is active for a send, Keplars injects a Reply-To header into the outbound email at send time:

From: [email protected]
Reply-To: [email protected]
Subject: Your order has shipped

When the recipient clicks Reply in their mail client, the compose window opens addressed to [email protected] instead of [email protected]. Keplars is not involved in the reply at all. The message goes directly to whatever inbox owns that address.

Using Reply-To in API Sends

Reply-To is opt-in for API sends. Add "reply_to": true to your request body to inject the header:

{
  "to": ["[email protected]"],
  "subject": "Your order has shipped",
  "body": "Your package is on its way.",
  "reply_to": true
}

If reply_to is omitted or set to false, no Reply-To header is added even if your workspace has an address configured. This applies to all priority endpoints: /instant, /high, /async, /bulk, and /batch.

Configure Reply-To

Open Tracking Settings

Sign in to dash.keplars.com
Navigate to Settings → Tracking
Scroll down to the Reply-To Address card

Enter Your Address

Enter the email address where replies should be delivered (e.g. [email protected]).

Any valid email address works: Gmail, Outlook, a shared team inbox, or a custom domain address.

Save

Click Save. The address is applied immediately to all subsequent sends from the workspace.

Verify It Is Working

Send a test email via the API and inspect the raw message headers. The Reply-To header should be present:

curl --request POST \
  --url https://api.keplars.com/api/v1/send-email/instant \
  --header 'Authorization: Bearer YOUR_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "to": ["[email protected]"],
    "subject": "Test reply-to header",
    "body": "Reply to this email to test.",
    "reply_to": true
  }'

In your email client, open the received email and view the raw source or original message. You should see:

Reply-To: [email protected]

Pro Tip: Most email clients surface the Reply-To address automatically. In Gmail, the reply compose window shows the Reply-To address instead of the From address. In Outlook it appears in the To field when you click Reply.

Edit or Remove

To change the address, go back to Settings → Tracking → Reply-To Address and click Edit.

To remove it entirely, click Remove. After removal, outbound emails will no longer include a Reply-To header and recipients' replies will go to whatever address is in the From field.

Removing the Reply-To address takes effect immediately on the next send. Emails already delivered are not affected.

Per-Campaign Reply-To

When creating a campaign, Step 1 includes a Reply-To Address field. It is prefilled from your workspace setting and can be overridden for that specific campaign.

Leave it as-is to use the workspace default.
Enter a different address to override it for this campaign only.
Clear the field entirely to send this campaign with no Reply-To header, regardless of the workspace setting.

Common Use Cases

Use case	From address	Reply-To address
Transactional emails	`[email protected]`	`[email protected]`
Marketing campaigns	`[email protected]`	`[email protected]`
Shared team inbox	`[email protected]`	`[email protected]`
Personal inbox (Gmail/Outlook)	Any sending address	`[email protected]`

What Keplars Does Not Do

No inbox interception: Keplars does not read, store, or process replies. The reply goes directly from the recipient's mail server to the Reply-To address.
No DNS setup: Unlike custom sending domains, the Reply-To address requires no domain verification, SPF records, or DKIM keys.
No SES receipt rules: Replies do not pass through Keplars infrastructure at any point.

Next Steps

Custom Domains - Send from your own domain instead of a shared address
Webhooks - Get real-time notifications about delivery, opens, and clicks
Send Emails - Learn about priority queue endpoints

Reply-To Address

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