Roundcube reads your mail; SOGo runs your calendars, contacts and phone synchronisation as well. If your users only need to read email in a browser, Roundcube 1.7.2 is lighter, simpler and has a bigger plugin ecosystem. If they need shared calendars, address books, and Thunderbird or a phone that syncs properly through CalDAV, CardDAV or ActiveSync, Roundcube cannot do that and SOGo is built for it. The cost of SOGo is a database, a Java-era runtime and considerably more to operate.
They solve different problems
Roundcube is a client. It connects to your IMAP server, renders messages, sends through SMTP, and stores almost nothing of its own beyond preferences and contacts. Remove it and your mail is untouched — every mailbox still works from Thunderbird or a phone.
SOGo is a server. It owns calendars and address books, stores them in its own database, and exposes them over CalDAV, CardDAV and ActiveSync so that native clients synchronise rather than merely reading. Remove it and you lose the calendars, because they lived there.
That difference in ownership drives everything: how much they cost to run, how badly each one breaks, and how hard they are to migrate away from.
What you get
| Roundcube | SOGo | |
|---|---|---|
| Current version | 1.7.2 / 1.6.17 (5 July 2026) | 5.12.9 (27 May 2026) |
| Reads IMAP mail | Yes | Yes |
| Calendars | Plugin, basic | Native, shared, with free/busy |
| Address books | Personal, plus LDAP | Native, shared, CardDAV |
| Phone / desktop sync | No | CalDAV, CardDAV, ActiveSync |
| Resource footprint | Light — PHP and a database | Heavier — its own daemon plus a database |
| Plugin ecosystem | Large and mature | Small |
| Typical use | Hosting webmail for customers | Teams and organisations |
ActiveSync is the row that decides most real cases. If somebody wants their work calendar on an iPhone without installing anything, that is ActiveSync, and no amount of Roundcube plugins produces it.
What each costs you to operate
Roundcube is close to free in operational terms. It is PHP behind your existing web server with a small database. It upgrades in minutes, its failure mode is that webmail is unavailable while IMAP keeps working, and any hosting panel can install it without thinking.
SOGo is a service with opinions. It runs its own daemon, it wants a properly tuned database, and integrating it with Postfix and Dovecot takes real configuration. Its failure mode is worse too: when SOGo is down, calendars and contacts are down for everyone, including phones that were syncing fine an hour ago.
That is the trade to weigh. You are not choosing between two webmail clients — you are deciding whether to take on a groupware service.
Security, in both directions
Both projects patch, and both have needed to.
Roundcube 1.7.2 and 1.6.17, on 5 July 2026, fixed a zero-click stored XSS in plain-text rendering (CVE-2026-54433), a stored XSS through an unescaped attachment MIME type (CVE-2026-54432), two SSRF bypasses, several password-plugin issues and a denial of service in TNEF handling.
SOGo 5.12.8, on 12 May 2026, fixed four reported vulnerabilities including two XSS issues triggered by malicious mail; 5.12.9 followed on 27 May to clean up regressions from that release.
The pattern is identical and unsurprising: both render hostile HTML sent by strangers, which is one of the most dangerous jobs in web software. Neither project's record should push you toward the other. What should influence you is that SOGo's blast radius is larger — a compromise there reaches calendars and contacts for the whole organisation, not just one mailbox view.
The SOGo 6 question
SOGo 6 was published on 17 July 2026 and the project calls it an alpha, warning of bugs and missing features. It is a complete rewrite: Python backend, Next.js frontend, PostgreSQL required, a task agent on Celery and Redis, and an administration API replacing the old sogo-tool command line.
Read that list as an operator rather than as a developer. A rewrite of this scope means new bugs in code paths that were stable for a decade, a migration of the calendar and contact tables, and a stack with more moving parts. It is a healthy direction for a project that had been running on ageing foundations, and it is not where production calendars belong in 2026. Plan for 5.12.x now and revisit when the project ships something it calls stable.
Choosing
Roundcube if you host mailboxes for customers who want browser access to email. It is the right default, it is what most hosting panels ship, and adding SOGo to that scenario means operating a groupware server for people who wanted webmail.
SOGo if you are running mail for an organisation where shared calendars and phone synchronisation are actual requirements. In that setting Roundcube is not a cheaper option, it is an incomplete one.
Both is legitimate in exactly one case: SOGo for the staff who need groupware, Roundcube as the light webmail everyone else gets. Some hosts run precisely that split. Just know you are maintaining two things.
Whichever you pick, the part that actually decides whether people are happy is not the client. It is deliverability — whether mail from your server reaches inboxes at all. Our guide to SPF, DKIM and DMARC covers that, and the broader options are in our comparison of Roundcube alternatives.
Frequently asked questions
Is SOGo better than Roundcube?
For calendars, shared address books and phone synchronisation, yes — Roundcube does not offer those. For simply reading email in a browser, Roundcube is lighter, simpler to operate and has a far larger plugin ecosystem. They target different problems.
Can Roundcube do calendars?
Only through plugins, and the result is basic and personal rather than shared. It cannot provide CalDAV or ActiveSync synchronisation to phones and desktop clients, which is usually the actual requirement behind the question.
Can SOGo and Roundcube run on the same server?
Yes. They connect to the same IMAP server independently and do not conflict, which is why some hosts offer SOGo to staff and Roundcube to everyone else. It does mean maintaining and updating two applications.
Does SOGo support ActiveSync?
Yes, alongside CalDAV and CardDAV, which is its main advantage: phones and desktop clients synchronise mail, calendars and contacts natively without extra software.
Is SOGo 6 ready for production?
No. The 17 July 2026 public release is described by the project as an alpha with bugs and missing features expected. It is a ground-up rewrite with a Python backend, Next.js frontend and PostgreSQL requirement. Production deployments should stay on the 5.12.x line.