Computer and Technology Blog

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With the phishing attempts that consonantly target users your company can get exposed to a possible infiltration because a user thought a representative of the company sent them an email asking to change the password or to cleanup a full inbox, etc. In the email they will have a link and a login page that is used to collect the users login name and password. Many companies are starting to implement some kind of indication to the user that the email originated outside the company. Some will add a tag to the subject like [EXTERNAL] if the mail system has capabilities for using transport rules, spamassasin header, postfix header_checks. Other phishing attempts would use CEO names in the name field with a different return email address. The way users fall for this is they do not look at the originating email address. It also does not help that most mail clients will only show display name when provided instead of the email. Currently zimbra does not have a way to creat...

for incoming email not from our domain (external domains) we want to add [EXTERNAL] to the subject but if it already contains [EXTERNAL] we do not want to add it again. I made the changes on our Sophos UTM 9 system.  More than likely it will require rewriting these files after a update.  This should apply to other systems running exim. If your exim is installed in chroot enviroment you want to place the files there on Sophos UTM this is /var/chroot-smtp/etc/ on system with non chroot it may be /etc/exim/ created a file /var/chroot-smtp/etc/exim.system_filter with following contents change domains to match your enviroment.  The > placed on the end of the match sstring so it does not match email address spoofing in display name using your domain.  /var/chroot-smtp/etc/exim.system_filter if $header_from: does not contain "@yourdomain.com>" and $header_from: does not contain "@yourdomain.localdomain>" and $header_from: does not contain ...

In an earlier post I mentioned how to tag/add EXTERNAL to the subject header on exim.  I made the changes on our Sophos UTM which may require re-applying the configuration files after Sophos UTM update. I ended up adding and elif block to act on outgoing emails in the exim.system_filter file this is the block I added.  Change your domain as appropriate and add additional lines if you need to. elif  $header_from: contains "@yourdomain.com>"  and $header_to: does not contain "@yourdomain.com>"  and $header_subject: contains "[EXTERNAL]" then  headers add "Old-Subject: $h_subject:"  headers remove "Subject"  headers add "Subject: ${sg{$h_old-subject:}{[[]EXTERNAL[]]}{}}"  headers remove "Old-Subject" endif This is the full exim.system_filter file To have the $h_from or $header_from act on the domain part and not the display name part if someone was trying to spoof the from name I added the > at the ...

Do the domain that was created by default is not the domain that you intended.  Or when you setup zimbra you were not paying attention and server name got added in front of the domain ie mail.domain.com instead of just domain.com. Now you need to setup the ham, spam, galsync, and virus-quarantine accounts to your new domain. Lets start with ham and spam. From zimbra webadmin find the spam and ham accounts under manage and then search individually for ham and spam.  They will have random characters after the name.  We will need the full name of both accounts.  Right click to edit the account and under account name change the domain to your newly created domain and save.  Do this for both accounts.  Also get the names of both accounts.  You can copy and paste them to use in the following command line. As zimbra user on the mail server run these commands. You can also check the current spam accounts with zmprov gcf zimbraSpamIsSpamAccount zimb...

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