Webmail with Roundcube

Roundcube is the webmail frontend in Plesk. No mail client needed — you log in via the browser and have access to your mailbox. Ideal on the go, from someone else’s computer, or simply as a companion to your mail client.

Webmail URL

With the Plesk default:

https://webmail.deinedomain.de

Or via Plesk: Domain → Mail → click the mailbox → webmail icon opens it already logged in.

Login

• Username: the full mail address (info@deinedomain.de)
• Password: the mailbox password

With the “stay logged in” option, Roundcube stores the login in browser cookies. Careful on other people’s computers — log out after use.

What you see in Roundcube

• Left sidebar: folder list (inbox, sent, spam, trash, your own)
• Center: mail list
• Right: the selected mail
• Toolbar at the top: actions (reply, forward, delete, etc.)

The UI is responsive — it also works in a smartphone browser.

Writing mail

Toolbar → Compose.

Editor features:

• Recipients (with auto-completion from the address book)
• CC / BCC
• Subject
• Plain-text or HTML editor
• Attachments
• Signature (configurable in advance in the settings)
• Save as draft
• Encryption (PGP, with the Mailvelope browser extension)

Address book

Left sidebar → Contacts.

You can:

• Create contacts manually
• Learn them automatically from mail recipients
• Import from vCard / CSV
• Export

While composing: auto-completion from the address book.

Filters / rules

Roundcube uses Sieve for server-side mail filters — filters run on the server, not in the client.

In Settings → Filters → Create filter:

• Condition: if sender, subject, header, etc.
• Action: move to folder, forward, auto-reply, discard

Example: put all newsletters with a List-Unsubscribe header into a Newsletter folder:

require ["fileinto"];
if header :contains "List-Unsubscribe" "" {
    fileinto "Newsletter";
}

Filters run on the server for all clients at once (webmail, iPhone, Outlook, etc.).

Auto-responder (out-of-office)

In Settings → Filters → Out-of-Office or directly in the Plesk mailbox settings.

• Date from / to
• Subject of the auto-reply
• Message body

Roundcube automatically sends the reply to senders during the period.

Signature

In Settings → Identities → edit identity:

• Signature text
• HTML formatting allowed
• Gets appended automatically under new mails

Multiple identities are possible (e.g. “private” and “business”) — switchable while composing.

Customizing the appearance

In Settings → Appearance:

• Theme (light / dark / Sky)
• Font size
• Layout (three columns or classic)

Using it in a mobile browser

Roundcube is responsive — a smartphone browser shows a mobile-optimized UI:

• Reduced toolbar
• Touch gestures (swipe for actions)
• Full-screen mail view

Handy on the go without a mail app.

Advantages over a mail client

• No setup needed: just a browser, login, go
• Available on any device: internet cafe, library, someone else’s PC
• Edit Sieve filters inline: no mail client settings needed
• Central address book: lives with the mailbox account, no local sync

Disadvantages compared to a mail client

• No offline use
• No push notifications (unless a browser tab is open)
• No encryption with local keys (except the Mailvelope extension)
• Performance with large mailboxes (>10 GB) slower than Outlook/Apple Mail

PGP with Mailvelope

Mailvelope is a browser extension for PGP encryption in Roundcube and other webmail frontends.

Setup:

1. Install the Mailvelope extension (Chrome / Firefox / Edge)
2. Generate a key pair in Mailvelope
3. Give the recipient your public key
4. When composing, Mailvelope detects the Roundcube compose field → encryption available

Works for PGP inline and PGP/MIME.

Frequently asked questions

Roundcube shows a login screen instead of automatic login from Plesk? When calling webmail.deinedomain.de directly, you have to log in. When opening from Plesk → mailbox → webmail icon, you get auto-login.

Login problems — what to do? Full mail address as the username, the mailbox password. If it still fails: Plesk mailbox settings → reset the password.

Roundcube settings are gone after reinstalling the browser. Settings are stored server-side (not browser cookies). They should survive. If they’re gone: open a ticket.

Can I put Roundcube on my own subdomain (mail.eigene-domain.de)? That’s the standard — with the Plesk setup, the webmail.<domain> variant is configured automatically.

How large can attachments be? PHP’s upload_max_filesize sets the limit — 64 MB (Start) to 1 GB (Max) depending on plan. Details in Choosing a PHP version. Practical note: many receiving mail servers reject mails over 25 MB — better share large files as a link.

Roundcube updates: does Plesk handle those? Yes. Roundcube updates come with Plesk updates or as separate updates. You don’t have to do anything.

Can I see multiple mailboxes in one Roundcube login? Roundcube itself is single-account. But you can create “identities” for multiple sender addresses. For real multi-account: use a mail client.

Roundcube themes / branding for club or company sites? Standard themes are available. Custom branding is possible on request — open a ticket.

What’s next

• Mail aliases, forwarding, auto-responders
• Setting up mail in a mail client
• Creating a mailbox