---
title: "10.2 Reply-To Mailboxes (Contact Communication)"
description: "A Reply-To Mailbox is an IMAP, POP3, or OAuth inbox configured so that campaign replies and direct contact emails flow to a specific user. Each mailbox is…"
url: "https://peikly.com/docs/reply-to-mailboxes-contact-communication/"
updated: "2026-10-07"
category: Email
tags:
  - Manual sync
---

# 10.2 Reply-To Mailboxes (Contact Communication)

## What This Feature Does

A Reply-To Mailbox is an IMAP, POP3, or OAuth inbox configured so that campaign replies and direct contact emails flow to a specific user. Each mailbox is assigned to one user — only that user can see and respond to emails in that mailbox.

## When to Use

- Use when you want campaign recipients to be able to reply to your campaigns.
- Use when a specific agent handles email conversations for certain contacts.
- Do not use this for sending bulk campaigns — that is the Outbound Mail Server.

## Prerequisites

- CompanyAdmin role (to configure).
- TenantUser role (to use — as the assigned user).
- Pro plan.
- Inbound mailbox credentials (IMAP/POP3) or OAuth authorization (Gmail, Outlook).

## 10.2.1 Supported Mailbox Types

**IMAP (standard)**

- Any email provider that supports IMAP
- Typical host examples: `imap.gmail.com`, `imap.outlook.com`, `mail.yourprovider.com`
- Port: 993 (SSL) or 143 (STARTTLS)

**POP3 (standard)**

- Any provider that supports POP3
- Typical host: `pop.gmail.com`, `pop.yourprovider.com`
- Port: 995 (SSL)

**Gmail OAuth**

- No password required
- Click **Connect with Google** and authorize the Gmail mailbox
- Application uses OAuth 2.0 to access the inbox securely

**Outlook OAuth**

- No password required
- Click **Connect with Microsoft** and authorize
- Uses OAuth 2.0; works with Microsoft 365 and Outlook.com accounts

---

## 10.2.2 Add a Reply-To Mailbox

1. In the sidebar, click **Email** → **Mailboxes**.
2. Click **Add Reply-To Mailbox**.
3. Fill in the **Inbound Settings** section:
   - **Provider:** IMAP, POP3, Gmail OAuth, or Outlook OAuth
   - **Host**, **Port**, **Username**, **Password** (for IMAP/POP3)
   - Or: click **Connect with Google / Microsoft** (for OAuth)
4. Fill in the optional **Outbound SMTP** section (for sending replies):
   - If left blank, replies use Gmail/Outlook OAuth channel natively.
   - For IMAP/POP3: provide SMTP host, port, username, password.
5. Set the **Display Name** and **Reply-To Email** address shown to recipients.
6. Choose the **Assigned User** (the user who will see this mailbox's emails).
7. Click **Save**.

## 10.2.3 Test the Mailbox Connection

1. After saving (or while creating), click **Test Inbound Connection**.
2. Application attempts to connect using the provided credentials.
3. Click **Test Outbound Connection** to verify SMTP settings.

**Messages:**

- Success feedback shown in the connection test result area.
- Error details shown if connection fails (e.g., wrong password, incorrect host, SSL mismatch).

## 10.2.4 Assign or Reassign a Mailbox

- Only CompanyAdmin can assign a mailbox to a user.
- Go to **Edit Reply-To Mailbox** and change the **Assigned User** dropdown.
- The new assignee immediately starts seeing incoming emails in their Email Conversations view.

## 10.2.5 Mailbox Health Warnings and Paused Sync

Application monitors Reply-To Mailboxes during automatic inbox sync. If a mailbox cannot authenticate, the system retries automatically up to three times for that mailbox.

If the mailbox still cannot connect after the third authentication failure:

- the mailbox row shows a warning state such as **Sync warning (1/3, 2/3)** while retries are still in progress, or **Sync paused** after the retry cap is reached
- the most recent sync error and time are shown on the mailbox row
- CompanyAdmin users receive a notification in the **Notification Bell** dropdown and **All Notifications** page
- the **Email** menu in the left navigation can show a warning badge so the issue is visible without opening the mailboxes page

How the warning clears:

- a successful **Test Inbound Connection** or successful mailbox validation clears the warning
- a later successful background inbox sync also clears the warning automatically
- after recovery, the mailbox warning notification is removed from active notifications

## Errors, Messages, and Common Fixes

| Message | Why It Happens | How to Fix |
| --- | --- | --- |
| `Mailbox not found.` | Deleted or access denied | Reload the mailboxes list |
| `Could not create/update mailbox.` | Validation or server error | Check all required fields |
| Connection test failed | Wrong host, port, or credentials | Verify credentials in your email provider's settings |
| Gmail OAuth: `Access denied` | Gmail security blocks app | Enable Less Secure App Access (deprecated) or use Google OAuth flow |
| Outlook OAuth: `AADSTS error` | Microsoft tenant policy restriction | Ask IT admin to grant OAuth app consent |
| `Sync warning (1/3)` or `Sync warning (2/3)` | Automatic inbox sync failed to authenticate and is retrying | Verify credentials, OAuth grant, host, port, and SSL/TLS settings before the mailbox reaches the pause limit |
| `Sync paused` | The mailbox failed to authenticate 3 times and automatic inbox sync has been paused | Open the mailbox, correct the configuration, and run **Test Inbound Connection** or save a working OAuth reconnection |

## Best Practices

- Use OAuth for Gmail and Outlook — it is more secure and reliable than password-based IMAP.
- Create one Reply-To Mailbox per agent when each agent has their own customer base.
- If you have one shared inbox, assign it to a team lead who coordinates responses.
- Match the Reply-To email address to the actual mailbox address to avoid confusion.
- Treat **Sync warning** badges as early warning signs. Fix the mailbox before it reaches **Sync paused** so inbox replies keep flowing without interruption.