ChemIT notes on specific situations where we have noticed Outlook outperforming Mail.

Microsoft Outlook provides a single application for email, calendar, and contacts.  Apple mail uses 3 different applications for the same functions. The single MS Outlook application provide tighter integration, and some additional features, as well as better overall performance. Synchronization of Outlook across multiple devices has also proven more reliable. Apple mail sometimes corrupts, and does not sync contacts or message folders correctly.

Specific situations ChemIT strongly recommends using Microsoft Outlook on the Mac

You have a reasonable amount of email.

• Performance languishes in Apple mail with just several thousand email messages.
  • Behaviors: Slow, unresponsive, unreliable/ gets confused

These problems are more common for users with large amounts of mail, especially a large IN box.

You have administrator responsibilities

• Outlook's calendar integration is often beneficial.
• Features for accessing group calendars, and managing rooms are not available in Apple iCal

You use a Cornell "special mailbox"

• Outlook handles it better than Mail does.