Blocked Attachments

Our virus and spam scanners are configured to block certains types of dangerous or potentially dangerous email attachments.  One of the major reasons that an email attachment gets blocked is because the file name has multiple extensions. For example, it may be called "my_holiday.jpg.exe" or "picture.gif.gif.scr".

If your attachment has been blocked by our virus scanners, you have 2 options;

1.  Rename the file and try re-sending it
If your file is called "fred.bloggs.file.pdf" rename it to "fred_bloggs_file.pdf" so that there is only one dot in the file name.

2.  Zip the file up and try re-sending it
There are many programs out there that can zip a file.  Add your file to a zip file, and try re-sending it.  If you name your file with 2 extensions (e.g. ""), it's still going to be blocked, so try giving it a name with only one dot, such as "".

Why do we block incorrectly named files?

Multiple file extensions exploit a vulnerability in MS Windows and MS Outlook where the attachment can appear using the icon of one extension (eg. a JPG image icon) but when the user opens it, is executed using another extension. Usually the last extension is used when opening the attachment, so a ".jpg.exe" file will appear to be a harmless JPEG image in MS Outlook but is really an executable program.

MS Outlook Express has a worse bug when there are three extensions: the first and last extensions are used for the icon, but it opens the file using the middle extension type: a file named ".jpg.bat.jpg" will be executed as a batch file. There are few legitimate uses of multiple file extensions in the Windows world!

If someone sends you a file with multiple file name extensions, it will be blocked and the sender will be notified. Please let the sender know that they are using a dangerous file naming convention, and that they will need to rename the file before sending it to you.

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