Mailcow on GCP - Developer Guide

Welcome to the Meetrix Mailcow developer guide for Google Cloud Platform! Mailcow bundles Postfix, Dovecot, SOGo webmail, Rspamd, and ClamAV into a single self-hosted mail server, so you get business email, custom domains, and webmail without wiring five separate services together yourself. With the Meetrix pre-configured GCP image, that whole stack is installed and talking to each other the moment the VM boots.

This guide walks you through finding the product on GCP Marketplace, configuring the deployment, reserving a static IP, pointing DNS and DKIM/SPF/DMARC at your server, adding your first domain, and accessing webmail.

Mailcow Mail Server on GCP Marketplace by Meetrix - Deploy in Minutes

Deploy a self-hosted Mailcow mail server on Google Cloud Platform in minutes. Meetrix's pre-configured GCP Marketplace solution bundles Postfix, Dovecot, SOGo webmail, and spam filtering, fully under your control.

By Shalomi Umeshika • Meetrix.io

Launch the Product

Step 1: Find the Product

1. Log in to your Google account.
2. Go directly to the product page: Mailcow Mail Server: Self Hosted Email Platform on Ubuntu
3. You can also browse all Meetrix products at the Meetrix Solutions Page.
4. You will see the product listing page. Click Get started.

Step 2: Accept the Agreements

1. Confirm your GCP project is selected.
2. Tick the box under Terms and agreements to accept the Google Cloud Marketplace and Meetrix Pte Ltd terms of service.
3. Click AGREE.

Free Trial

This product includes a 5-day free trial with up to USD 50.00 in licence fee credits. To activate it, tick I accept the solution trial Terms and Conditions on the launch screen before proceeding.

Step 3: Configure the Deployment

You will see the deployment configuration form, with Terraform and Command-Line deployment tabs. Fill in the fields across the following sections:

General

• Deployment name — A unique name for this deployment.
• Deployment Service Account — Use an existing service account with the compute.admin, config.agent, and iam.serviceAccountUser roles, or create a new one.
• Zone — Select the GCP zone closest to your users (e.g. us-central1-a).
• Machine type — Default e2-standard-2 (2 vCPU, 8 GB RAM) is a solid starting point for a small team's mail traffic. Scale up if you expect heavier mailbox counts or attachment volume.

Boot Disk

• Boot disk type — Default Balanced persistent disk is recommended.
• Boot disk size — Default 32 GB is a reasonable starting point; increase it if you expect large mailboxes or long retention.

Networking

• Network / Subnetwork — Leave as default unless you have a custom VPC.
• External IP — Leave as Ephemeral for now. You will reserve a static IP before pointing DNS at the server.
• Allow SSH (TCP port 22) — Enabled by default. Restrict the source IP range if you want to limit SSH access to specific IPs.

Once the fields are filled in, follow the on-screen instructions in your chosen tab (Terraform or Command-Line deployment) to deploy, and wait a few minutes for the deployment to complete.

Reserve a Static IP

1. Open the VM instance created by the deployment and note the External IP under Network interfaces — it is marked (Ephemeral).
2. In the GCP console, go to VPC network → IP addresses, find that same address, and click Reserve Static Address (or promote it directly from the VM instance details page).
3. Copy the reserved external IP — you will use it for your A, MX, and PTR records.

Point DNS to the Server

Mail delivery and SSL both depend on DNS being correct before you go further:

1. Add an A record pointing your mail hostname (e.g. mail.yourdomain.com) to the reserved static IP.
2. Add an MX record for your sending domain pointing at that hostname.
3. Ask your hosting or network provider to set a matching reverse DNS (PTR) record for the static IP — this matters for deliverability.
4. Wait for DNS propagation before proceeding (typically a few minutes to 1 hour).

SSH into the Server

1. Go to the VM instance page in the GCP console.
2. Click SSH to open a browser-based terminal and authorize access.

Access the Mailcow Admin Panel

Once DNS has propagated and the instance has issued its SSL certificate, open https://<your-mail-hostname>/admin in your browser and log in with the default admin credentials from your deployment. You land on the System & Containers dashboard, showing hostname, version, CPU, memory, and disk usage for the instance.

The E-Mail menu in the top navigation gives you quick access to mail-specific settings — Configuration, Quarantine, Queue Manager, and a Restart SOGo option if webmail ever needs a kick.

Add Your First Domain

Step 1: Open the Domains Tab

Go to Domains in the admin panel. On a fresh deployment this list is empty.

Step 2: Add the Domain

1. Click + Add domain.
2. Enter your Domain (the same one you pointed DNS at).
3. Set Max. possible aliases, Max. possible mailboxes, and the mailbox quotas to whatever fits your team size.
4. Leave the DKIM Selector as dkim and DKIM key length at 2048 bits unless you have a specific reason to change them.
5. Click Add.

Step 3: Publish DKIM, SPF, and DMARC

After the domain is added, open it in the Domains list and click the DKIM key icon to reveal the generated public key. Publish it as a TXT record at dkim._domainkey.yourdomain.com, then add the SPF and DMARC TXT records Mailcow recommends for your domain.

Step 4: Create a Mailbox

Go to the Mailboxes tab, click + Add mailbox, choose the domain you just added, and set a username and password. The mailbox is ready to receive mail as soon as DNS and DKIM have propagated.

Access Webmail

SOGo webmail is bundled with the image and reachable at the same hostname. Log in with any mailbox you created to send and receive mail directly from the browser, with calendars and address books included.

Manage the Server

Restart the Services

sudo docker restart <container_name>

Shut Down the VM

To stop the VM without deleting it, go to Compute Engine → VM Instances in the GCP console, select your instance, and click Stop.

Delete the Deployment

To fully remove the deployment and stop all billing:

1. Go to Solution deployments in the GCP console.
2. Find your Mailcow deployment.
3. Click Delete to remove all associated resources.

Troubleshoot

Check the Service Logs

Mailcow runs on Docker. Find the running containers and check their logs:

sudo docker ps -a
sudo docker logs <container_name>

Verify Firewall Ports

In the GCP console, go to VPC Network → Firewall and confirm the following rules exist for your VM:

Mail Landing in Spam

Double-check that the DKIM, SPF, and DMARC TXT records match exactly what the admin panel shows for the domain, and confirm the PTR record for your static IP resolves back to your mail hostname. A new sending IP with no history will still take time to build reputation even with every record correct.

Conclusion

The Meetrix Mailcow developer guide helps you get a self-hosted mail server running on GCP without losing a weekend to Docker Compose files and DKIM key generation. Reserve a static IP, point DNS at it, add your domain, and you have a private alternative to per-seat hosted email running on infrastructure you control.

Technical Support

If you run into any issues, our support team is here to help. Reach out to us at support@meetrix.io and we will respond within 12 hours.