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Feature Comparison

E-mail, Calendaring & Integration		Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
Max. Number of Domains	Unlimited				Unlimited	900
Max. Number of Users	Unlimited				Unlimited	300
Active Directory Support (with SSO)
Archiving
Contacts, Shared and Public (GAL)
Calendars & Resource Management								3rd party
Tasks & Notes				Tasks only			Tasks only	3rd party
API Integration with External Systems
FTP Access								3rd party
White Label (for ISPs and enterprise customers)

The fact that our clients can use IceWarp on Linux CentOS liberates us from the need to pay for Microsoft Client Access Licenses (CALs).

Lim Seow Keang, CEO of MyTech

TeamChat		Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
Public & Private Channels	Unlimited					Public only
Free Guest Access
API Integration with Web Applications
Real-time Active Directory Sync
Video & Voice Calls (one-on-one)							3rd party	3rd party
Conferencing							3rd party	3rd party
Screen Sharing							3rd party	3rd party
Private Instant Messaging							3rd party

Storage	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
Online Document Editing (Word, Excel, PowerPoint ..)	Sharepoint online						3rd party
Opening, Editing & Saving in MS Office (Desktop)
Document Versioning	SharePoint Online				SharePoint Online		3rd party
Access Control Lists
WebDAV/SMB Protocols		WebDav Online		WebDav Online	WebDav Online	WebDav Online	3rd party
External Access to Files via URL Sharing	SharePoint Online
Group Sharing

The ability to support various mobile devices, regardless of their operating system, was one of the winning factors.

Joiey Nizar, Sales Director at VizOne

Apps & Mobile Access	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
IceWarp Desktop Office (Desktop Client, Documents, Spreadsheets and Presentations)
Desktop Documents Editing
Desktop Spreadsheets Editing
Desktop Presentations Editing
FileSync client for Windows	OneDrive		OX drive		OneDrive	Google Drive	3rd party
FileSync client for Mac	OneDrive		OX drive		OneDrive	Google Drive	3rd party
FileSync client for Linux
Mobile Messenger App for iOS	Skype					Hangouts
Windows Outlook Compatibility
MacOS Compatibility
Exchange ActiveSync support for mobile devices							3rd party
Remote Configuration App for Windows

The support is something that really sets IceWarp apart from all others. We did this project on a very tight schedule and were successful.

Valerie Schafer, IT Director at Z-AXIS

Security	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
Spam Filtering
Integrated Antivirus

Support	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack	Exchange Zimbra Open Xchange Kerio Connect Office 365 Google Apps Slack
Online Help
Office Hours Support		phone
24/7 Phone Support