Blocked Attachment Types

For security purposes, a number of attachment types are blocked by default by Microsoft Office 365.  These types are those where the risk of malicious content is significant - and the legitimate use of the file types are limited.  The list of attachment types are below.  They are subject to change without notice as risk conditions warrant.


Microsoft Office - Macro Enabled File Types

  • .docm, (Word)
  • .ppsm, .pptm .sldm (Powerpoint)
  • .xlam, .xlm (Excel)

Executable Content Types:

  • .com
  • .dll
  • .dos
  • .exe
  • .jar
  • .obj
  • .os2
  • .pif
  • .rar
  • .vbe
  • .vxd
  • .w16

Other file types:

  • .ace (extremely uncommon compressed file type)
  • .ani
  • .app
  • .reg (Microsoft Registry File)
  • .w16
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Article ID: 49261
Wed 2/28/18 10:20 AM
Mon 5/13/24 2:50 PM