---
title: "Automatically Blocked Network Ports | Hostman Docs"
description: "Learn which network ports are automatically blocked on new Hostman servers to prevent abuse like spam and DDoS attacks. See the full list and how to request access."
---

> For the complete documentation index for AI agents, see [llms.txt](https://hostman.com/llms.txt).

To prevent abuse, we automatically block certain network ports when a new server is created. 

This helps protect the infrastructure from being misused for spam, DDoS attacks, or unauthorized access.

We block the following ports by default:

-   **25, 465, 587, 2525**: email-related ports that are commonly used for sending spam;
-   **3389, 389, 53413**: ports commonly exploited for attacks (e.g., DDoS, credential theft, backdoors).

You can check which ports are blocked on your server via the server **Dashboard**. 

![Image1](https://content.hostman.com/assets/eb6e5160-de7e-4c76-8850-e3e7f34967b8.png?width=1520&height=1524)

> [!NOTE]
> The list reflects only those ports blocked by Hostman automatically; if you manually blocked specific ports on your server, they won’t be displayed on the dashboard.

If you're using your server for legitimate purposes and need access to one of the blocked ports, contact our support team via the chat in your dashboard—we’ll review your request and lift the restriction if appropriate.

### Blocked Ports FAQ

#### What port does SMTP use?

SMTP commonly uses ports 25, 465, and 587, as well as the alternate port 2525. 

#### What is the SMTP port number for encrypted email?

The standard SMTP encrypted port is 587, which supports STARTTLS. Ports 465 and 2525 are used for implicit SSL/TLS encryption. 

If you're unsure whether to use SMTP port 587 vs 25, select port 587 if you need to send email from a client application with login authentication.

#### Dashboard doesn’t show any blocked SMTP ports but I cannot send email from my server. Why?

You may have blocked the ports manually. You can test SMTP using the command line tools like `telnet`:

```shell
telnet <server IP address> <port number>
```

For example:

```shell
telnet 166.1.227.100 587
```

You can also use the hostname instead of the IP address:

```shell
telnet yourdomain.com 587
```

If the port is blocked, the connection will fail. 

#### Can I open the SMTP ports 25, 465, 587, 2525 on my server?

Yes, if you are using the server for legitimate purposes, contact our support team and request unblocking.

#### SMTP ports on my server are open, but email still isn't being sent. What could be the issue?

You may have configured your SMTP server incorrectly. 

You can run an SMTP server check using external tools such as [smtper.net](https://www.smtper.net/), [gmass.co](https://www.gmass.co/smtp-test), etc. There are many others, you can easily find them on the web.

They allow you to quickly check SMTP configuration online and verify authentication, encryption, and delivery settings.

#### What are ports 3389, 389, and 53413, and why are they blocked by default?

Port **3389** is used for Remote Desktop Protocol (RDP), which is often targeted in brute-force and credential-theft attacks. 

Port **389** is typically used for LDAP (Lightweight Directory Access Protocol). It's a known target for enumeration and exploitation attacks, especially when not properly secured.

Port **53413** is rarely used for legitimate services but is often reported as being used by malware or for creating hidden remote access (backdoors).