Every Business email package comes with

Migration and Converters
Mail server converters for a wide variety of competitors
Mailbox migration for email, calendar, contacts and tasks
Automation (Web Services/SOAP)
Compatible with wide variety of control panel companies
Add/edit domains users
Add/edit calendars, tasks and notes
Add/edit RSS feeds
Collaboration
Webmail reminders system
Webmail availability of attendees
Webmail personal contacts
Webmail personal calendars, tasks and notes
Mail Server Protocols
SMTP
IMAP4 and IMAP IDLE
POP3
Message retrieval via POP and IMAP
Anti Spam Measures
Incoming and outbound spam checking
Spam quarantine (outgoing messages only)
Spam checking on POP3 message retrieval
Outgoing spammer detection and limiting
SPF record checking
RBL listing detection
Reverse DNS checking
Greylisting (based on IP, sender location, spam weight, etc.)
DKIM Mail Signing
Configurable spam headers
Trusted senders
Requiring SMTP authentication for outgoing messages
Antivirus
Out-of-the-box ClamAV
Support for third-party real-time antivirus solutions
Support for third-party command-line antivirus solutions
Security/Attack Prevention
Incoming and outgoing TLS
Incoming and outgoing SSL
Optional alternate SMTP port
SMTP authentication by domain
Restrict administrator access via IP
Brute force detection for Webmail
Manual and automatic IP whitelisting/blacklisting
Automatic harvest attack prevention
Automatic denial of service prevention
Malicious script filtering in webmail
Throttle user and domain activity
Throttle incoming bounces to prevent saturation
Web Interface (Webmail)
Multi-language compatible
Optimized AJAX controls provide desktop application performance
Compatible with mobile devices
Preview message attachments
New message notifications from anywhere in interface
Thumbnails for image file attachments
Download all attachments as .ZIP
Upload attachments in the background
File storage
Automatic save as draft
Click-to-map, click-to-call and click-to-mail functionality
Follow-up flagging
Linked emails and tasks
Advanced content filtering
Advanced spam filtering rules
User-level auto-clean
Support for multiple languages
Email address auto-complete similar to Microsoft Outlook
Import and export contacts
Support for user and domain aliases
Multiple signatures support
Multiple identity/SMTP support
Mailing Lists
Bounce detection
Automatic removal of subscribers on bounces
Optional double opt-in
Subscriber custom fields
Friendly unsubscribe links in messages
Common subscriber database for all mailing lists
Merge variables and custom fields into messages (mail merge)
Toggle auto-generated response to mailing list commands
Enhanced mailing list compose with attachments
Customized command messages
Mail logging per subscriber