When comparing Roundcube vs Kontact, the Slant community recommends Roundcube for most people. In the question“What are the best native e-mail clients for Linux?” Roundcube is ranked 8th while Kontact is ranked 9th. The most important reason people chose Roundcube is:
Licensed under GPL v3 with code available on [GitHub](https://github.com/roundcube/roundcubemail).
Ranked in these QuestionsQuestion Ranking
Pro Free and open source
Licensed under GPL v3 with code available on GitHub.
Pro Plug-in support
Pro Sophisticated address book
Each contact can have their e-mail address, phone number, location, photos and associated URLs added to them. You can then group contacts and address your mails to the group instead of having to enter each person separately. Additionally, you can import vCards and CSV files as contact information. And, it has LDAP connectors.
Pro Drag & drop support
Roundcube supports attaching files simply by dragging and dropping them in.
Roundcube is available in over 70 languages.
Pro Access control support
Roundcube has built-in support for access control lists (ACL).
Pro Built-in caching
Roundcube caches messages to allow quicker access to your mailbox and to alleviate the strain put on the server. You can turn off caching (change 'enable_caching' property in your config/main.inc.php file) if you need messages to appear instantly.
Pro Multiple identities
You receive mail from multiple sources in one account.
Has auto-refresh functionality for email boxes.
Pro Good documentation
You have access to the documentation for APIs as well plugins development.
Pro Spell checking
You can enable/disable spellcheck by changing "enable_spellcheck" in main.inc.php file.
Fully supports PGP and S-MIME with built-in certificate management. Encrypt, sign and verify emails easily and securely.
Pro Multi-account, multi-identity
Supports both multiple accounts from different servers / services simultaneously (both inbound and sending) as well as multiple identities. Incoming accounts have a default identity and it switches automatically to the correct identity depending on the mail folder you are in.
Pro Integrated calendaring
The integrated calendaring support means that incoming invitations can be accepted with a click and they get put into your calendar automatically.
Pro Contacts, Todos, Notes, Journals, Feeds ....
There are numerous components that come with Kontact that augment the mail experience including contact management, todo lists, note takers and an RSS feed reader, among others.
Pro Supports multiple groupware servers and services
Besides being able to connect to any IMAP, POP3 and SMTP server, you can also connect your Google and Facebook accounts and access Kolab and Tine servers natively.
Pro Continuous, active development
Kontact has been actively developed for over a decade, with components such as the mail and calender going back even further. Development continues to this day with an active and responsive open source community made up of both volunteers and paid developers behind it.
Pro Solid offline IMAP
IMAP support is a strong point for Kontact, with offline mail and sync being transparent and automatic. Read and create mails on the go and everything syncs quickly and reliably when network connectivity is available.
Pro Built-in search
Searching for emails is simple with the search box in the main window which can scan through email bodies, email flags, recipients, etc. Lightening fast in recent versions.
Pro Spam, scam and adblock features
Supports spam filtering, scam detection and adblock for HTML mails.
Pro Keyboard friendly
Can be driven almost entirely from the keyboard. Moving an email, for instance, is a simple matter of hitting 'm' and then typing to filter through the list of folders that appears.
Pro Plain text and HTML mail editing
Provides support for rich-text (HTML) mail editing, but kindly defaults to plain text. Also supports viewing HTML emails with several security features built-in.
Works on Linux/BSD (all desktop environments and window managers), Windows and Mac.
Has flexible and powerful options, from "traditional" conversation-style threading to organizing by date, by senders and receivers, .... paired with "keep replies in same folder" it is easy to track conversations over time.
Supports client and server-side filtering of mails by subject, recipients, mailing list, body text, etc.
Pro Very flexible user interface
You can make the Kontact UI look and function how you want. You can re-arrange the main interface, as well as make the list of mails show or hide almost anything you could need.
Pro Professional support
For enterprise deployments, having commercial support can be a big plus. Companies such as Kolab Systems provide professional support and consulting services for Kontact.
Pro Integration with kde plasma
Based on qt, and part of plasma suite, it integrates well with other KDE apps like kwallet, calendar, etc.
Not easy to create your own themes.
Con Moblie Use
Does not translate to mobile use very well
Con For search there is no reverse index
This means it is very slow.
Unfortunately, all interfaces of roundcube look very old. I hope there will be a progress soon, Google Mail and Outlook Webmail should be the role models here. But also Yahoo mail offers an intuitive design.
If this open source software should survive, it must be completely renewed and bring up to new standards.
Con Extremely clunky unintuitive interface
For example the mouse cursor may start getting stuck and lag.
Con Search option are limited
You can only search for one item at a time instead of multiple search terms, which makes it difficult to go through large amounts of emails.
Con You can't make multiple accounts
It is not possible to make more then one account.