1. 
BCM -  Business Contact Manager File
2. 
BCMX -  Business Contact Manager Customization
3. 
CLX -  Ceelox SecureMail Secure Message
4. 
CVR -  Microsoft Crash Report File
5. 
DAT -  Exchange E-mail Attachment
8. 
FFA -  Find Fast Status File
9. 
FFL -  Find Fast Document List
10. 
FFO -  Find Fast Document Properties Cache
11. 
FFX -  Microsoft Find Fast Index
12. 
GXK -  Galaxkey Secured File
13. 
HOL -  Outlook Holidays File
14. 
ICAL -  iCalendar File
17. 
KMR -  KnowledgeMill Link File
18. 
MBOX -  E-mail Mailbox File
19. 
MIM -  Multi-Purpose Internet Mail Message File
20. 
MIME -  Multi-Purpose Internet Mail Extension
21. 
MME -  Multi-Purpose Internet Mail
22. 
MMF -  Microsoft Message File
23. 
MS-TNEF -  MS Transport Neutral Encapsulation Format
24. 
MSG -  Outlook Mail Message
25. 
MSO -  Inline E-mail Attachment
26. 
NICK -  Outlook 2000 Nickname File
27. 
NK2 -  Outlook 2002 Nickname File
28. 
OAB -  Offline Address Book
29. 
OBI -  Outlook RSS Subscription File
30. 
OLK -  Outlook Address Book File
42. 
OLM -  Mac Outlook Database File
43. 
OSS -  Microsoft Outlook Saved Search File
44. 
OST -  Outlook Offline Folder File
45. 
OTM -  Outlook Macro File
46. 
P10 -  Certificate Request File
47. 
PAB -  Personal Address Book
48. 
PRF -  Preferences or profile file
49. 
PST -  Outlook Personal Information Store File
50. 
PWI -  Pocket Word Document
51. 
RGE -  Entourage File Archive
52. 
RPMSG -  Outlook Restricted Permission Message
53. 
RWZ -  Outlook Rules Wizard File
55. 
TNEF -  Transport Neutral Encapsulation Format
57. 
VCS -  vCalendar Event File
58. 
WAB -  Windows Address Book
59. 
XST -  Microsoft Outlook personal folders file