---
title: Sample Domain Setup
description: Graymutt@nucking-futz.com
published: true
date: 2026-03-16T00:34:08.387Z
tags: 
editor: markdown
dateCreated: 2026-02-25T22:02:27.719Z
---

# Mail Setup — nucking-futz.com

## Part 0 — OPNsense: Configure ATT_Mail Secondary IP

Before configuring DNS or Mailcow, the secondary AT&T static IP must be configured in OPNsense as a virtual IP on the WAN interface and NAT rules must be set so only raw SMTP traffic (ports 25, 465, 587, 993, 143) uses this address. Webmail, the Mailcow admin UI, and all other traffic continue to use the primary WAN IP (107.133.34.145).

| Address | Purpose |
|---------|---------|
| 107.133.34.145 | Primary WAN — web, admin, everything else |
| 107.133.34.146 | ATT_Mail — SMTP/IMAP inbound and outbound only |

### Step 0.1 — Add Virtual IP

1. Go to **Interfaces → Virtual IPs → Settings**
2. Click **+ Add**
3. Set the following:

| Field | Value |
|-------|-------|
| Mode | IP Alias |
| Interface | WAN (igc1) |
| Network / Address | `107.133.34.146 / 28` |
| Description | `ATT_Mail` |

4. Click **Save**, then **Apply changes**

> The /28 subnet mask matches the AT&T block (107.133.34.144/28). All 5 static IPs in the block share this mask.

### Step 0.2 — Outbound NAT for SMTP Traffic

This ensures Mailcow's outbound SMTP connections leave through the ATT_Mail IP rather than the primary WAN IP. OPNsense must be in **Hybrid** or **Manual** outbound NAT mode.

1. Go to **Firewall → NAT → Outbound**
2. Confirm mode is set to **Hybrid Outbound NAT** (or Manual — either works)
3. Click **Add** to create a new rule

**Rule for outbound SMTP (port 587 relay to MXRoute):**

| Field | Value |
|-------|-------|
| Interface | WAN |
| TCP/IP Version | IPv4 |
| Protocol | TCP |
| Source | `192.168.5.16 / 32` (Mailcow host) |
| Source Port | any |
| Destination | any |
| Destination Port | 587 |
| Translation / Target | `107.133.34.146` (ATT_Mail) |
| Description | `Mailcow outbound relay via ATT_Mail` |

4. Repeat for port **25** (direct outbound SMTP, if used) and port **465** (SMTPS)
5. Click **Save** and **Apply changes**

### Step 0.3 — Inbound NAT (Port Forwards) for Mail Ports

Route inbound connections on mail ports to Mailcow using the ATT_Mail IP as the external address.

1. Go to **Firewall → NAT → Port Forward**
2. Create rules for each mail port:

| External IP | Port(s) | Forward to | Description |
|-------------|---------|-----------|-------------|
| 107.133.34.146 | 25 | 192.168.5.16:25 | SMTP inbound |
| 107.133.34.146 | 465 | 192.168.5.16:465 | SMTPS inbound |
| 107.133.34.146 | 587 | 192.168.5.16:587 | Submission inbound |
| 107.133.34.146 | 993 | 192.168.5.16:993 | IMAPS |
| 107.133.34.146 | 143 | 192.168.5.16:143 | IMAP (if needed) |

> **Do not** add port forwards for 80, 443, or 3443 (Mailcow admin/webmail ports) on this IP. Those remain on the primary WAN IP via Caddy.

3. Click **Save** and **Apply changes**

### Step 0.4 — Firewall Rules

Ensure the WAN firewall rules permit inbound traffic on the mail ports to the ATT_Mail IP. If you have a default deny-all WAN rule (recommended), add explicit pass rules:

1. Go to **Firewall → Rules → WAN**
2. Add pass rules for each port in the table above with destination `107.133.34.146`

### Step 0.5 — Verify

```bash
# From outside your network, confirm the mail IP is live
telnet 107.133.34.146 25
# Should see: 220 hermes.netgrimoire.com ESMTP

# Confirm primary WAN IP does NOT respond on port 25
telnet 107.133.34.145 25
# Should time out or be refused

# Check that Mailcow outbound connections leave from the ATT_Mail IP
# Send a test to check-auth@verifier.port25.com and inspect the Return-Path
# or check the Received: header — the sending IP should be 107.133.34.146
```

> ⚠ If the verify step shows port 25 still responding on 107.133.34.145, check that no leftover port forward rules exist on the primary WAN IP for mail ports.

---

## Overview

This guide covers complete mail setup for `nucking-futz.com` using MXRoute as the inbound gateway and Mailcow as the mailbox host. MXRoute receives all inbound mail from the internet (solving residential IP filtering issues with banks and financial institutions) and forwards to Mailcow for storage and retrieval. Mailcow handles outbound mail via the MXRoute SMTP relay.

**Architecture:**

```
Inbound:  Internet → MXRoute (commercial IP) → Mailcow (192.168.5.16)
Outbound: Mailcow → MXRoute SMTP relay → Internet
```

**Why two domains in Mailcow:**
MXRoute forwarders require a valid destination email address. You cannot forward `graymutt@nucking-futz.com` back to `graymutt@nucking-futz.com` — that loops. The solution is to have Mailcow own a subdomain (`mail.nucking-futz.com`) with its own MX record pointing directly to your server. MXRoute forwards to `graymutt@mail.nucking-futz.com`, Mailcow delivers locally, and an alias domain maps `nucking-futz.com` back so users only ever see and use `graymutt@nucking-futz.com`.

---

## Prerequisites

- MXRoute account active with DirectAdmin access
- Mailcow running at 192.168.5.16
- DNS management access for nucking-futz.com
- Your MXRoute server hostname from your MXRoute welcome email (e.g. `arrow.mxrouting.net`)

---

## Step 1 — DNS Records

Create all DNS records before configuring either service. Keep TTL at 300 during setup — raise to 3600 once confirmed working.

![image.png](/image.png)

![arec.png](/email/arec.png)

![txt.png](/email/txt.png)

### Required DNS Records

| Type | Host | Value | Notes |
|------|------|-------|-------|
| A | `mail` | `YOUR_ATT_MAIL_IP` | Points to Mailcow — MXRoute forwards to this server |
| MX | `@` | `heracles.mxrouting.net (Priority 10)` | Check MXRoute welcome email for exact hostname |
| MX | `@` | `heracles-relay.mxrouting.net (Priority 20)` (priority 20) | Secondary MXRoute server from welcome email |
| MX | `mail` | `mail.nucking-futz.com` (priority 10) | Mailcow handles this subdomain directly |
| CNAME | `imap` | `mail.nucking-futz.com` | Client autoconfiguration |
| CNAME | `smtp` | `mail.nucking-futz.com` | Client autoconfiguration |
| CNAME | `webmail` | `mail.nucking-futz.com` | Roundcube access |
| CNAME | `autodiscover` | `mail.nucking-futz.com` | Outlook autodiscover |
| CNAME | `autoconfig` | `mail.nucking-futz.com` | Thunderbird autoconfig |
| TXT | `@` | `v=spf1 ip4:YOUR_ATT_MAIL_IP include:mxroute.com -all` | SPF — authorizes both Mailcow direct and MXRoute relay |
| TXT | `mail` | `v=spf1 ip4:YOUR_ATT_MAIL_IP -all` | SPF for subdomain — Mailcow sends directly from here |
| TXT | `_dmarc` | `v=DMARC1; p=reject; rua=mailto:admin@netgrimoire.com` | DMARC enforcement |

> DKIM TXT records (two selectors) are added in Steps 2 and 3 after generating keys in Mailcow and MXRoute.

---

## Step 2 — Mailcow Configuration

### 2.1 Add the Subdomain as Primary Domain

Mailcow owns `mail.nucking-futz.com` as its active mail domain. Mailboxes live internally on this subdomain.

1. Log into Mailcow admin UI → **Mail Setup → Domains**
2. Click **Add domain**
3. Set **Domain:** `mail.nucking-futz.com`
4. Leave all other settings as default
5. Click **Add domain**

### 2.2 Add the Alias Domain

This makes Mailcow accept mail addressed to `@nucking-futz.com` and deliver it to the matching `@mail.nucking-futz.com` mailbox. Users send and receive as `@nucking-futz.com` — the subdomain is invisible to them.

1. Go to **Mail Setup → Alias Domains**
2. Click **Add alias domain**
3. Set **Alias Domain:** `nucking-futz.com`
4. Set **Target Domain:** `mail.nucking-futz.com`
5. Click **Add**

### 2.3 Create Mailbox

1. Go to **Mail Setup → Mailboxes**
2. Click **Add mailbox**
3. Set **Username:** `graymutt`
4. Set **Domain:** `mail.nucking-futz.com`
5. Set a strong password
6. Set quota as needed
7. Click **Add**

The mailbox is internally `graymutt@mail.nucking-futz.com`. The alias domain from Step 2.2 means Mailcow also accepts and delivers mail for `graymutt@nucking-futz.com` to this same mailbox.

### 2.4 Generate DKIM Key

1. Go to **Configuration → Configuration & Diagnostics → Configuration**
2. Click **ARC/DKIM Keys** tab
3. Select domain `mail.nucking-futz.com`
4. Set **Selector:** `mailcow`
5. Set **Key length:** 2048
6. Click **Generate**
7. Copy the full TXT record value — needed for DNS

### 2.5 Add Mailcow DKIM DNS Record

| Type | Host | Value |
|------|------|-------|
| TXT | `mailcow._domainkey.mail` | *(full key string from Mailcow — begins with `v=DKIM1;`)* |

### 2.6 Add MXRoute to Trusted Networks

Prevents Mailcow from applying spam scoring to forwarded mail arriving from MXRoute's IPs.

1. Go to **Configuration → Configuration & Diagnostics → Configuration**
2. Click **Extra Postfix configuration** tab
3. Add to `extra.cf`:

```
# Trust MXRoute forwarding IPs
mynetworks = 127.0.0.1/8 [::1]/128 192.168.5.0/24 69.167.160.0/19 198.54.120.0/22
```

> Verify current MXRoute IP ranges in your MXRoute account documentation — these may change.

4. Click **Save**
5. Click **Restart affected containers**

### 2.7 Configure Outbound Relay

Routes outbound mail through MXRoute for best deliverability.

1. Go to **Configuration → Routing → Sender-Dependent Transports**
2. Click **Add transport**
3. Set **Domain:** `nucking-futz.com`
4. Set **Relay host:** `[smtp.mxroute.com]:587` (confirm SMTP hostname from MXRoute welcome email)
5. Set **Username:** your MXRoute relay username
6. Set **Password:** your MXRoute relay password
7. Click **Add**
8. Repeat for domain `mail.nucking-futz.com` using the same relay credentials

---

## Step 3 — MXRoute Configuration

### 3.1 Add Domain in DirectAdmin

1. Log into MXRoute DirectAdmin
2. Go to **Account Manager → Domain Setup**
3. Add domain: `nucking-futz.com`
4. Complete the domain wizard

### 3.2 Create Forwarder

MXRoute does not support domain-level remote MX routing — forwarders must be created per address. The destination must be on a domain whose MX resolves to Mailcow, not back to MXRoute.

1. Go to **Forwarders** in the MXRoute control panel
2. Click **Create New Forwarder**
3. Set **Forwarder Name:** `graymutt` (the `@nucking-futz.com` part is shown automatically)
4. Set **Destination Type:** `Forward to Email(s)`
5. Set **Recipients:** `graymutt@mail.nucking-futz.com`
6. Click **Create Forwarder**

> Every new mailbox requires a matching forwarder entry. The pattern is always `user@nucking-futz.com` → `user@mail.nucking-futz.com`. See the Adding a New Mailbox section below.

### 3.3 Get MXRoute DKIM Key

1. Go to **Email Manager → DKIM Keys** for `nucking-futz.com`
2. Generate or view the DKIM key — note the selector name assigned (often `x`)
3. Copy the full TXT record value

### 3.4 Add MXRoute DKIM DNS Record

| Type | Host | Value |
|------|------|-------|
| TXT | `x._domainkey` *(replace `x` with MXRoute's actual selector)* | *(full key string from MXRoute DirectAdmin)* |

---

## Step 4 — Verify DNS

Once DNS has propagated, verify all records:

```bash
# MX for main domain — should show MXRoute servers
dig MX nucking-futz.com +short

# MX for subdomain — should show mail.nucking-futz.com
dig MX mail.nucking-futz.com +short

# A record — should show your ATT IP
dig A mail.nucking-futz.com +short

# SPF
dig TXT nucking-futz.com +short
dig TXT mail.nucking-futz.com +short

# DMARC
dig TXT _dmarc.nucking-futz.com +short

# DKIM — Mailcow
dig TXT mailcow._domainkey.mail.nucking-futz.com +short

# DKIM — MXRoute (replace x with your selector)
dig TXT x._domainkey.nucking-futz.com +short
```

Run a full check at [https://mxtoolbox.com](https://mxtoolbox.com) → Email Health for `nucking-futz.com`.

---

## Step 5 — Test Mail Flow

### Inbound Test

Send a test email to `graymutt@nucking-futz.com` from an external Gmail or Outlook account. Verify:

- Mail arrives in the Mailcow mailbox
- Headers show the MXRoute → Mailcow forwarding path (two `Received:` hops)
- No spam flagging

In Roundcube open the test message → **More → View Source** and check the `Received:` chain.

### Outbound Test

Send from `graymutt@nucking-futz.com` to an external Gmail address. Run through [https://mail-tester.com](https://mail-tester.com) for a full delivery score.

### DKIM/SPF/DMARC Test

Send a test to `check-auth@verifier.port25.com` — you will receive an automated reply confirming pass/fail for SPF, DKIM, and DMARC.

### Bank/Financial Test

Send from a bank address to `graymutt@nucking-futz.com` and confirm delivery. This is the primary goal — banks see MXRoute's commercial IPs in the MX record, not your residential AT&T IP.

---

## Email Client Settings

| Setting | Value |
|---------|-------|
| Email address | `graymutt@nucking-futz.com` |
| IMAP server | `mail.nucking-futz.com` |
| IMAP port | `993` (SSL/TLS) |
| SMTP server | `mail.nucking-futz.com` |
| SMTP port | `465` (SSL/TLS) |
| Username | `graymutt@nucking-futz.com` |
| Password | *(mailbox password set in Step 2.3)* |

> Users log in and send as `graymutt@nucking-futz.com`. Mailcow resolves this to the internal `mail.nucking-futz.com` mailbox transparently via the alias domain.

---

## Adding a New Mailbox

Every new address on `nucking-futz.com` requires entries in both Mailcow and MXRoute.

**In Mailcow:**
1. Mail Setup → Mailboxes → Add mailbox
2. Username: `newuser`, Domain: `mail.nucking-futz.com`

**In MXRoute control panel:**
1. Forwarders → Create New Forwarder
2. Forwarder Name: `newuser`, Destination Type: `Forward to Email(s)`, Recipients: `newuser@mail.nucking-futz.com`

---

## Credentials Reference

| Service | Account | Password |
|---------|---------|----------|
| Mailcow mailbox | `graymutt@mail.nucking-futz.com` | *(set during mailbox creation)* |
| MXRoute relay | *(from MXRoute welcome email)* | *(from MXRoute welcome email)* |
| MXRoute DirectAdmin | *(from MXRoute welcome email)* | *(from MXRoute welcome email)* |

---

## Known Gotchas

**Forwarder destination must not loop.** Never set the MXRoute forwarder destination to an address on the same domain that has MXRoute as its MX. `graymutt@nucking-futz.com` → `graymutt@nucking-futz.com` will loop. Always forward to `@mail.nucking-futz.com` which has its own MX resolving directly to Mailcow.

**Two DKIM selectors required.** `mailcow._domainkey.mail.nucking-futz.com` covers mail Mailcow sends directly from the subdomain. `x._domainkey.nucking-futz.com` (MXRoute selector) covers outbound mail relayed through MXRoute. Both must exist for DMARC to pass on all paths.

**New mailboxes need matching MXRoute forwarders.** MXRoute has no catch-all forwarding to remote servers. Every address that needs to receive mail must have an explicit forwarder in DirectAdmin. Add the MXRoute forwarder step to your mailbox creation checklist.

**Alias domain vs. alias mailbox.** The alias domain in Step 2.2 maps the entire `nucking-futz.com` domain to `mail.nucking-futz.com`. Do not also create individual alias mailboxes for the same addresses — this creates duplicate delivery and may cause unexpected behavior.

**SPF differs between the two domains.** The main domain SPF includes `include:mxroute.com` because MXRoute relay sends outbound from there. The subdomain SPF (`mail.nucking-futz.com`) only needs your ATT IP — Mailcow sends directly from that domain without going through MXRoute. Two different records for two different send paths.

---

## Related Documentation

- [MailCow Configuration](./mailcow)
- [MXRoute Outbound Relay Setup](./mxroute-outbound-relay)
- [OPNsense Firewall](./opnsense-firewall) — static IP allocation for ATT_Mail
