Edit the file /usr/mailscanner/etc/filename.rules.conf and add the following lines near the bottom of the file,
immediately above the lines denying double file extensions.
allow \.rel$ - -
allow \.xml\.rel$ - -
Please note that the spaces between the fields
must be TAB characters and not SPACES.
You may also want to or need to add specific exceptions for doc.rel
files or whatever other type of office document your users need to send
or receive. Just make a similar rule to the second one, for instance
with "\.doc\.rel$" instead of "\.xml\.rel$".
Alternatively, if you wish to allow all double file extensions (which
is a risk but if you are having lots of these legitimate files blocked,
and are also using virus scanning and filetype checking it may be a
risk worth taking), you can change the rule regarding all double file
extensions. It is usually the last line of
/usr/mailscanner/etc/filename.rules.conf and it will look like this:
deny \.[a-z][a-z0-9]{2,3}\s*\.[a-z0-9]{3}$ Found possible filename hiding
Simply change the "deny" to "allow", save the file, and restart
MailScanner as below. Again, make sure that the spaces between the
fields are TAB characters and not SPACES.
Once you have finished editing and saved the file (you should edit it
on the server with vi or pico/nano, rather than on your PC), restart
MailScanner either via the WHM front-end or in shell with the following
command:
service MailScanner restart