Roundcube filters are powerful rules that automatically sort, forward or edit your email. Instead of organizing every message by hand, you let filters do the work. In this article, we explain how to set up filters and get the most out of them.

What are Roundcube filters?

Filters are "if-then" rules:

  • If a message meets certain conditions
  • Then perform an action

For example:

  • If sender = nieuwsbrief@bol.com → Move to folder "Newsletters"
  • If subject contains "Invoice" → Mark as important
  • If message is larger than 10MB → Move to folder "Large files"

Filters run automatically on the server. They also work when you're not logged in.

Setting up filters in Roundcube

Step 1: open the filter settings

  1. Log in to Roundcube webmail
  2. Click "Settings" (gear icon)
  3. Select "Filters" in the left menu

You now see an overview of your existing filters (or an empty list).

Step 2: create a new filter

  1. Click the "+" icon or "Add filter"
  2. Give the filter a recognizable name
  3. Set the conditions ("If")
  4. Set the action ("Then")
  5. Click "Save"

Filter conditions ("If")

You can filter on:

Sender (From)

  • is equal to - Exact match (newsletter@company.nl)
  • is not equal to - Everything except this address
  • contains - Part of the address (@company.nl)
  • not contains - Excludes a domain

Recipient (To)

Handy if you have multiple email addresses:

Subject

  • contains - Keyword in the subject ("Invoice", "Order")
  • is equal to - Exact subject line
  • matches - Regex pattern (advanced)

Size

  • greater than - Messages above a certain size
  • less than - Messages below a certain size

Handy for separating messages with large attachments.

Date

  • older than - Messages from more than X days ago
  • newer than - Recent messages

Headers (advanced)

Filter on technical headers:

  • X-Spam-Score: for spam filtering
  • X-Priority: for urgent messages
  • List-Unsubscribe: for mailing lists

Combining conditions

You can combine multiple conditions:

"All conditions must be true" (AND)

  • Sender contains @webshop.nl AND subject contains "Order"
  • Both must match

"One of the conditions must be true" (OR)

Filter actions ("Then")

Move to folder

The most commonly used action. Automatically moves a message to a folder.

Examples:

  • Newsletters → folder "Newsletters"
  • Messages from your boss → folder "Important"
  • Messages with "ticket" → folder "Support"

Copy to folder

Makes a copy in another folder; the original stays in your inbox.

Handy for:

  • Backups of important messages
  • Messages that belong in multiple folders

Delete

Delete immediately (to the trash) or delete permanently.

Be careful! Permanently deleted mail can't be recovered.

Mark as read

Automatically mark as read. Handy for:

  • Automated notifications you don't need to read
  • Newsletters you only archive

Mark with a flag

Adds a flag/star. Handy for:

  • Messages that need attention
  • Messages from important contacts

Forward

Automatically forwards a message to another address.

Examples:

  • Forwarding support messages to a colleague
  • A copy to a CRM system

Note: Some hosting providers limit forwarding to prevent spam.

Reply with a message

Send an automatic reply. Handy for:

  • Vacation autoresponder
  • Confirmation of receipt

Use sparingly - automatic replies can look like spam.

Stop processing

Stops filter processing after this rule. Important if you have multiple filters that may overlap.

Practical filter examples

Sorting newsletters

Name: Newsletters Condition: Sender contains "newsletter" OR sender contains "nieuwsbrief" OR header "List-Unsubscribe" exists Action: Move to folder "Newsletters"

Archiving invoices

Name: Invoices Condition: Subject contains "invoice" OR subject contains "factuur" OR subject contains "payment" Action: Move to folder "Accounting/Invoices", Mark with a flag

Blocking spam from known spammers

Name: Spam block Condition: Sender is spam@example.com OR sender contains "lottery" Action: Delete (permanently)

VIP treatment

Name: Important contacts Condition: Sender is equal to boss@company.nl OR sender is equal to big-client@partner.nl Action: Mark with a flag, Move to folder "Priority"

Large attachments separately

Name: Large files Condition: Size greater than 5MB Action: Move to folder "Large files"

Mail from a specific customer

Name: Customer ABC Condition: Sender contains "@customerabc.nl" Action: Move to folder "Customers/ABC"

Filter order and priority

Filters run in order from top to bottom. This matters:

  1. Spam filter - Deletes spam
  2. VIP filter - Flags important mail
  3. Sorting - Moves messages to folders

If a message matches multiple filters, all actions are performed (unless you use "Stop processing").

Changing the order

In the filter overview, you can drag filters up or down to change the order.

Sieve: the technical foundation

Roundcube filters use Sieve, a standard scripting language for mail filtering. If you see the "Edit filter set" option, you can write Sieve code directly.

Example Sieve script:

require ["fileinto", "imap4flags"];

if address :contains "from" "@newsletter.nl" {
    fileinto "Newsletters";
    stop;
}

if header :contains "subject" "invoice" {
    addflag "\\Flagged";
    fileinto "Accounting";
    stop;
}

For most users, the graphical interface is enough.

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Testing filters

After creating a filter, test it:

  1. Send a test message that meets the conditions
  2. Wait 1-2 minutes
  3. Check whether the message was processed correctly
  4. Adjust the filter if needed

Troubleshooting

Filter doesn't work

Check:

  • Is the filter active? (the checkbox must be on)
  • Is the condition exactly right? (Watch out for capitalization with "is equal to")
  • Is the filter high enough in the list?
  • Does your server support Sieve?

Mail disappears

If mail doesn't arrive:

  1. Check your Spam/Junk folder
  2. Check the folders your filters move mail to
  3. Check that no "Delete" filter is active

Filters aren't executed

This can mean:

  • Sieve isn't active on the server
  • There's a server error
  • Contact your hosting provider

Filters vs. spam filter

Roundcube filters are for manual rules. The spam filter (SpamAssassin) at the server level works automatically.

Use filters for:

  • Sorting legitimate mail
  • VIP treatment
  • Archiving

Let the spam filter:

  • Detect and delete spam
  • Block phishing

You can combine both: the spam filter catches spam, then your filters sort the rest.

Frequently asked questions

Do filters also work on my phone? Yes! Filters run on the server, so they work no matter how you read your mail.

Can I export/import filters? Not by default in Roundcube. If you edit the Sieve source, you can copy the code and paste it elsewhere.

How many filters can I have? This depends on your hosting provider. Usually dozens of filters are no problem.

Can I filter by attachment name? This requires advanced Sieve extensions that aren't available everywhere. Check with your provider.