Last modified: 2026 January 26

---

Overview

Roundcube has built-in features for identifying and organizing unwanted email within its Junk mailbox. When you turn on spam filtering, Roundcube sends suspicious emails to this mailbox. You can then delete the spam or move back any emails that aren’t actually spam.

What is the Junk mailbox?

The Junk mailbox is a default directory (like Inbox or Sent) designated to store spam or unwanted messages.

To navigate to the Junk mailbox, select Mail from the navigation bar and then select Junk.

How to set up spam filters

Roundcube does not have a spam‑scanning engine. Instead, it relies entirely on a server‑side spam filter, such as Apache SpamAssassin™, to determine whether a message is spam.

The server-side filter will deliver spam to the designated system directory, and Roundcube will display these messages in the Junk mailbox.

For more information, read our Spam Filters documentation.

Mark messages as spam or ham

Apache SpamAssassin maintains learning databases for both spam and ham, allowing it to improve accuracy over time.

You can use Roundcube’s Junk () and Not Junk () buttons to send training signals to Apache SpamAssassin. These actions tell your filter which messages are spam and which are legitimate. Apache SpamAssassin will use this data to make better decisions about future incoming mail.

To mark the message as spam and move it to the Junk mailbox, perform the following steps:

1. Select the message.
2. Click the Junk () button in the toolbar.

To mark the message as ham and remove it from the Junk mailbox, perform the following steps:

1. Select the message.
2. Click the Not Junk () button in the toolbar.

Delete all spam messages

The Empty Junk () button moves all spam messages in your Junk mailbox to the Trash folder.

To completely delete all spam messages, perform the following steps:

1. Navigate to the Junk mailbox.
2. Click Empty Junk ().
3. Click Delete to confirm your decision. All spam messages will be moved to the Trash folder.
4. Navigate to the Trash folder and click Empty.