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Proofpoint, Inc.

Essentials Filters: File extensions

Situation You encounter an unknown file extension and want to learn what program or file uses that extension. You may be creating or using filters for specific attachment types and need to know what extensions to target.
Solution See below for a list of all filter file extensions. These are helpful to know which extension applies to specific attachment type filters.

Attachment Type filter

If you need assistance creating filters, please review this article: Essentials Filters: Expanded overview

From the filters, using the Attachment Type option gives you this pop-up.


See the next section for some file types associated in each section. This is not a comprehensive list of all files, and some files (the more common ones) are cross pollinated. In addition, attachment extensions are not the only item filtered here; mime/types are also filtered as part of this. 

Reduce False Positives

To reduce false positives on this, we suggest creating a more customized filter: How to create a filter to block specific extensions

Support recommends this filter than using this library filter set.

Email Header 

In an email header, the mime section is not only checking for types, but also checks for the executables as well. 

List of file extensions:

Microsoft executables: .exe, .com
Microsoft binary libraries: .dll
Microsoft executable scripts: .bat, .pif, .scr
Visual Basic files: .vb, .vbe, .vbs
Other vulnerable Microsoft files: .chm, .hlp, .inf, .isp, .lnk, .msc, .msi, .msp, .reg, .shb, .shs, .wsc, .wsf, .wsh
Microsoft/Installshield Cabinet files: .cab
Java binaries: .jar
OS X DMG files: .dmg
OS X install scripts: .mpkg
Debian/RedHat packages: .deb, .rpm
MS Office, pre-2007: .doc, .xls, .ppt
XML, Zip, and newer Office docs: .zip, .docm, .docx, .dotm, .dotx, .pptx, .pptm, .potx, .potm, .ppam, .ppsx, .ppsm, .xlsx, .xlsm, .xltx, .xltm, .xlam, .odb, .odf, .odg, .odm, .odp, .ods, .odt, .otg, .oth, .otp, .ots, .ott
Microsoft Access: .accdb, .accde, .accdt, .accdr, .mda, .mdb, .mde, .mdt, .mdw, .mdz
Other *Office files: .doc, .dot, .xlsb, .xla, .xlb, .xlc, .xld, .xlk, .xll, .xlm, .xls, .xlt, .xlv, .xlw, .pcs, .pot, .ppa, .pps, .slk, .stc, .std, .sti, .stw, .sxc, .sxd, .sxg, .sxi, .sxm, .sxw, .wcm, .wdb, .wks, .wps, .wkb, .wpd, .wpt, .wp5, .wpf, .wpm
Rich Text Format files: .rtf
Tape archives: .tar, .cpio
Compressed files: .F, .gz, .bz, .bz2, .lzo, .Z, EMZ
Other compressed archives: .7z, .rar, .lha, .arj, .arc, .zoo, .sit
PDF files: .pdf
PostScript: .ps, .ai
TeX DVI files: .dvi
Macromedia Flash data: .swf
Images: .jpg, .gif, .png, .tif, .pcx, .bmp
Vector graphics: .svg, .eps
Windows Metafiles: .wmf
Cursors and icons: .ani, .cur, .ico
Multimedia/video containers: .wmv, .avi, .flv, .mkv, .ogg, .ogm, .mov
MPEG audio/video: .mpg, .mp2, .mp3, .mp4, .m4a, .aac
RealNetworks audio/video: .ra, .rm, .rv, .rmvb
Windows Media audio: .wma
FLAC audio: .flac
AIFF audio: .aif, .aiff, .aifc
WAVE audio: .wav
MIDI audio: .mid
JavaScript files: .js
PGP Encrypted data: not attachment, but a MIME
Undecipherable attachments: See this KB


If a filter is triggered against one of these, it could be due to a mime/type issue and not a specific file extension. Please see the earlier note on reducing false positives to create a filter on an extension instead.

In addition to these files you can create a filter with condition "Attachment Name" and include htm, html, htm., html. or any other extension not added into the extensions above.