Attachments extensions


Attachments extensions

WorldPosta server protection layers block a set of different file extensions in order to protect the receiver from any possibility to hurt his email system and to minimize the spamming risk. The most common blocked type is the executive file extension (.exe)

Some files could be blocked while they are not threatening your system but there was just a doubt of being harmful, while other harmful files could just pass these filters and not being removed.

So for the case of the valid file, you can agree with the receiver to upload this file to any trusted website, even on your company website if possible so you can avoid being blocked.

You may think and try to change the file name extension manually, well let me tell you that this may work and deceive some email servers but also this will not work with other servers’ antivirus systems such as WorldPosta email server as they still can detect the real file extension.


As a side note, it is also possible to find a normal Microsoft file blocked (.doc, .xlx, .ppt,….), well that’s because it may contain some macros or scripts

In this article, we will be listing some of the important extensions that you better not use while attaching a file to prevent being blocked.

- .exe: WorldPosta as an example by default block all attachments with that extension, the executive extension. Even if they are compressed or zipped
- .app : executable application
-.cmd: DOS command file
-.JS : JavaScript source code
-.chm: compiled html help
-.cnt: Help file index
-.cpl: Windows control Panel extension
-.hlp: windows help file
-.inf: information file
-.Ksh: UNIX shell script
-.maf: Access
-.tmp: Temporary files
-.URL: Internet location
-.jar: Compressed archive file package

And a lot more: .pl, .ocx, .mcf, .grp, .class, .cla, .ade, .xnk, .wsh

This list is not limited to these file extensions only; there are even more blocked files.