Set a Reply-To address on a mailbox

What it does

A Reply-To address lets a mailbox send an email while replies go somewhere else. When you set one, EmailPal adds a Reply-To header to the campaign emails that mailbox sends. When a lead clicks Reply, their email client fills in the Reply-To address instead of the mailbox address.

The header is signed along with the rest of the message, so it cannot be changed in transit. A lead can still edit the To field by hand, so a reply can end up at the mailbox anyway.

Set it in the dashboard

1. Open Mailboxes and choose the mailbox.
2. In its sending settings, enter the address under Reply-to address.
3. Save.

It applies to the next email the mailbox sends. Emails already sent keep the header they went out with. Clear the field and save to go back to receiving replies in the mailbox.

Set it with the API or MCP

Send reply_to to PATCH /api/public/v1/mailboxes/{id} with a write-scoped key, or to the update_mailbox tool in MCP. For example, the request body {"reply_to": "sales@yourcompany.com"} sets it. GET /mailboxes/{id} returns the current value as reply_to. Send null or an empty string to clear it.

What stops working when replies bypass the mailbox

EmailPal reads replies from the mailbox. A reply that goes to your Reply-To address never arrives there, so EmailPal does not see it. That means:

• Stop when a lead replies does not fire, and the lead keeps getting follow-ups unless you pause or remove them yourself.
• The reply does not appear in Unibox or the CRM, and no reply notification is sent.
• Replies that ask to be removed are not picked up as opt-outs.

If your team works replies in EmailPal, leave the field empty. If replies must go to another inbox, watch that inbox and stop the lead by hand.

Rules

• One address only. A list of addresses is not accepted. If you need two people to get a reply, point the Reply-To at a shared inbox or a forwarding address.
• An address equal to the mailbox's own address is ignored, because it adds nothing.
• Use an address on your own domain where you can. Some receivers read a Reply-To on a different domain from the sender as a mild warning sign.

What it does not cover

• Another tool's mail. The setting applies to campaigns sent by EmailPal's sequencer. If Instantly, Smartlead or another tool sends over SMTP with your exported credentials, set Reply-To in that tool. EmailPal passes the header through unchanged.
• Replies from Unibox. A reply you send from Unibox or the inbox API goes out without a Reply-To, so the conversation continues in the mailbox.

Need More Help?

SMTP and IMAP credentials, Campaign sending limits and mailbox rotation, Campaign lead states and stop rules.