Some common reasons organizations choose 01.com Zimbra hosting over Fusemail.com include:

1. 48 days of un-delete / roll-back / restore for each mailbox
2. Free/busy time scheduling
3. Native Blackberry sync (BES)
   
4. Delegated sharing and syncing shared resources like calendars and contacts
5. Native Mac mail, ical and addressbook sync (Tiger and Leopard)
6. Thunderbird sync mail, calendars and contacts
7. Mobile device over-the-air (OTA) sync, including iZimbra for the iPhone
8. Zimbra Desktop looks the same as the web interface, and provides off-line access to all of your Zimbra info, even shared information, for Windows, Mac and Linux
   

The following feature comparison is based on research as of January, 2009. We welcome your comments and suggestions to improve this table. Please note that we have listed current features, so this table will change as new features are released. Also note that this is not a strategic comparison. 

Features	01.com Zimbra Hosting	Fusemail Hosting
Recurring Fees	$49.99/user/year or $4.99/user/mo	$.99/user/mo (min $10 or $100/mo)
Maximum Number of Mailboxes	Unlimited.	Unlimited.
Bring Your Own Domain Names (yourcompany.com)
Domain Admin / User Provisioning & Management
Maximum quota (GB/mailbox)	Unlimited (Extra fees)	Unlimited (Extra fees)
Maximum attachment message size (MB)	50	50
Data Portability (move your data to another solution)	Open-standards based.	Proprietary.
Secure LDAP Information Lookup (Mail.app, Outlook, etc.)
Live support for Mac and Windows users	Included for every person with a mailbox.	With branding, only for 1 admin.
Mail folder sharing		Limited. (not delegated)
Secure Chat	(beta)	Jabber only (security?)
Off-line access in web-browser
CalDav & WebDav compliant
File sharing (including drag and drop to web!)		(FTP only)
Task list delegation/sharing		Sharing only.
Branding - Custom Logo	Free.	Limited. Extra fees.
Wiki / Document Sharing
Calendar sharing & delegation		Sharing only.
Contact sharing & delegation		Sharing only.
Global Address List (GAL/LDAP) - Company Address Book	Included.	Included.
Free/busy checking for group calendaring	Included.
Resources (IE: conference rooms, projectors)
LDAP - Open/Active Directory Integration
Instant, Self-Activation/Cancellation		Activation only.
Advanced, Personal Anti-Spam/Anti-Virus	Included. Or use your own.	Included.
Desktop Sync Support (Outlook, Mail, iCal, AddressBook)	Mac, Linux & Windows.	Outlook only.
Blackberry OTA sync (email, calendar, contacts)	Native BES (beta).	Additional software.
Free iPhone Support	(IMAP & iZimbra).	IMAP only.
Windows Mobile & Palm sync (email, calendar, contacts)	Optional.	Web browser only.
Web 2.0 Mash-up framework (Zimlets)	Included.	Limited.
Web Identities	Included. ( Sync to Outlook)	Included. (web-only)
Terms	Monthly. Cancel anytime.	Small biz: Monthly. Cancel anytime. Large biz: annual.
Service Level Agreement (SLA)	99.9%	99.95%
External POP/IMAP - Email account centralization
Distribution Lists (mailing lists)	Unlimited & free.	Unlimited & free.
Aliases	Unlimited & free.	Unlimited & free.
Optional "free" version with Ads and no 24/7 support.
Software as a Service (SaaS)
May be redeployed in-house, on your own servers.
Mining user data and other info (see privacy)
Keyboard/navigation short-cuts
Published Road Map		Limited.
Able to restore deleted message (rollback)	48 days!	10 days
SOX Compliance (Archiving & Discovery)	Optional. Built in!	Limited archiving only.
Free Trial	30 days	7 days
Public Systems Status Page	Visit it!