Custom Reply-To

Reply-To Email: Overview and Configuration Guide

1. What the Reply-To setting does

The Reply-To setting controls which email address receives replies from recipients.

Without a custom setting:

• Replies go to the mailbox sender address by default.

With custom Reply-To enabled:

• Outgoing emails include a Reply-To header using your configured custom address.

• Recipients who click “Reply” will reply to that custom address instead of the sender address in the From header.

2. Why this setting exists

A custom reply-to address is useful when you’re sending emails through SMTP-only providers such as AWS SES, Mailgun, or SendGrid, which are typically designed for outbound messaging and don’t handle incoming replies. By setting a reply-to address, you can direct all recipient responses to a separate inbox that you control, ensuring you actually receive and manage replies instead of losing them. This is especially important if you’re using a mailbox that supports both SMTP and IMAP, as our system relies on IMAP to sync incoming messages. Configuring a compatible reply-to address allows features like the unified inbox to function properly, giving you full visibility and control over email conversations.

This is useful when you want:

• A different inbox to receive responses.

• A centralized reply mailbox for one or many sender accounts.

• Better operational routing of responses without changing the visible sender identity.

3. Provider support

Custom Reply-To is supported for mailboxes connected though the custom SMTP option, OAuth connections like Zoho and Microsoft aren't supported.

Not supported:

• Google mailboxes

• Microsoft mailboxes

• Zoho mailboxes

For unsupported providers, the system continues using the sender email behavior.

4. Default behavior

Default state:

• Custom Reply-To is OFF.

• Reply behavior uses the sender email address.

No action is required unless you want replies routed elsewhere.

5. Critical requirement for Unibox sync

If you enable custom Reply-To on SMTP:

• The custom Reply-To address should be the same mailbox monitored by IMAP for that sender.

If they do not match:

• Replies may still be delivered to that custom address.

• Unibox may not ingest/sync those replies correctly.

6. How to configure (single mailbox)

1. Open the mailbox settings for an SMTP mailbox.

2. Go to General Settings.

3. Find the Reply-To section.

4. Enable “Use custom reply-to email”.

5. Enter the custom reply-to email address.

6. Save changes.

Validation enforced:

• The field cannot be empty when enabled.

• The value must be a valid email format.

• It must match the IMAP mailbox requirement used for reply ingestion.

7. How to configure (bulk update)

Bulk General Settings supports custom Reply-To for SMTP selections.

Behavior:

• Available only when all selected accounts are SMTP.

• If your selection includes non-SMTP accounts, bulk Reply-To update is unavailable.

• If you do not edit the Reply-To section, existing Reply-To values are left unchanged.

Bulk steps:

1. Select SMTP mailboxes.

2. Open Bulk General Settings.

3. Enable custom reply-to (optional).

4. Enter one custom reply-to email for all selected accounts.

5. Save bulk changes.

8. Sending behavior after configuration

For SMTP sends:

• If custom Reply-To is enabled and non-empty, outgoing email uses that address as Reply-To.

• Otherwise, it falls back to sender email.

This applies to:

• Campaign sends

• Single/manual SMTP sends

• SMTP test-send flows

9. Recommended best practices

• Use an actively monitored inbox as Reply-To.

• Keep Reply-To aligned with the IMAP mailbox used by your inbox sync pipeline.

• Test by sending to a personal inbox and clicking Reply.

• Confirm replies appear in Unibox before rolling out broadly.

• For teams, define a policy for when to use sender email vs shared reply mailbox.

10. Troubleshooting

Replies are not appearing in Unibox:

• Verify custom Reply-To matches the IMAP mailbox configured for that sender.

• Verify IMAP credentials and folder mapping are healthy.

• Confirm the mailbox is SMTP (feature is SMTP-only).

Cannot enable bulk Reply-To:

• Check selected accounts. All must be SMTP.

Validation error while saving:

• Ensure the Reply-To is a valid email address.

• Ensure it is not empty when custom Reply-To is enabled.

11. Quick FAQ

Does custom Reply-To change the From address?

• No. It only changes where recipient replies are routed.

If custom Reply-To is disabled, what happens?

• Reply behavior uses sender email as before.

Can I use this on Microsoft/Google/Zoho mailboxes?

• No. currently only custom SMTP connections support this.

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