Before you run **mailcow: dockerized**, there are a few requirements that you should check:
- **WARNING**: When you want to run the dockerized version on your Debian 8 (Jessie) box you should consider switching to the kernel 4.9 from jessie backports because there is a bug (kernel panic) with the kernel 3.16 when running docker containers with *healthchecks*!
- Mailcow: dockerized requires some ports to be open for incomming connections, so make sure that your firewall is not bloking these. Also make sure that no other application is interferring with mailcow's configuration.
- A correct DNS setup is crucial to every good mailserver setup, so please make sure you got at least the basis covered bevore you begin!

## Minimum System Resources

Please make sure that your system has at least the following resources:

| Resource                | mailcow-dockerized |
| ----------------------- | ------------------ |
| CPU                     | 1 GHz              |
| RAM                     | 1 GiB              |
| Disk                    | 5 GiB              |
| System Type             | x86_64             |

## Firewall & Ports

Please check if any of mailcow's standard ports are open and not blocked by other applications:

```bash
netstat -tulpn | grep -E -w '25|80|110|143|443|465|587|993|995'
```

If this command returns any results please remove or stop the application running on that port. You may also adjust mailcows ports via the `mailcow.conf` configuration file.

If you have a firewall already up and running please make sure that these ports are open for incomming connections:

| Service             | Protocol | Port   | Container       |
| --------------------|:--------:|:-------|:----------------|
| Postfix Submission  | TCP      | 587    | postfix-mailcow |
| Postfix SMTPS       | TCP      | 465    | postfix-mailcow |
| Postfix SMTP        | TCP      | 25     | postfix-mailcow |
| Dovecot IMAP        | TCP      | 143    | dovecot-mailcow |
| Dovecot IMAPS       | TCP      | 993    | dovecot-mailcow |
| Dovecot POP3        | TCP      | 110    | dovecot-mailcow |
| Dovecot POP3S       | TCP      | 995    | dovecot-mailcow |
| Dovecot ManageSieve | TCP      | 4190   | dovecot-mailcow |
| HTTP(S)             | TCP      | 80/443 | nginx-mailcow   |