Blocking .exe attachments with postfix or amavisd-new and ISPConfig 3

Wednesday, September 2, 2009 posted by admin

If you use postfix and / or amavisd-new on the mail server, you can use the following recipes to block emails with executable (exe, bat, scr) attachments.

Block the attachments with a postfix header filter

In ISPConfig, click on "Email in the upper menu, then on "Content filter" in the left menu and click on the "Add new content filter" button. Enter the following details:

Filter:

MIME-Header Filter

Regexp. Pattern:

/^Content-(Disposition|Type).*name\s*=\s*"?(.*\.(bat|exe|scr))(\?=)?"?\s*(;|$)/x

Data:

File extension is blacklisted on this server

Action:

DISCARD

Use amavisd-new to block the emails with executable attachments.

Edit the amavisd configuration file (/etc/amavisd.conf or /etc/amavisd/amavisd.conf)

vi /etc/amavisd/amavisd.conf

and add the following lines:

$banned_filename_re = new_RE(
qr'.\.(bat|exe|scr)$'i,
qr'^\.(exe|zip|lha|tnef)$'i,
);

then restart amavisd-new:

/etc/init.d/amavis restart

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3 Responses to “Blocking .exe attachments with postfix or amavisd-new and ISPConfig 3”

  1. Bjoern says:

    .com files should be blocked too.

  2. fbifido says:

    How do you block and send an email only to the recipient? and forward the block email to a specific address like remove@mydomain.com.

  3. delaflota says:

    Hi, Is it really a file type blocking or only a file extension one?
    I mean in both postfix and amavis-new…

    Thanks

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