Package: exim4-config
Version: 4.94.2-6
The default configuration provided by exim4-config allows for sieve
filters to be used in ~/.forward, but if a user attempts to configure
such a filter their mail delivery will most likely break.
More specifically, the keep action (including the default "keep" when
nothing matches the filter) will fail to deliver mail with an error
along the lines of
2021-05-30 15:17:10 1lnNBd-0000rr-U4 == save inbox <test@localhost>
R=userforward T=address_file defer (-21): appendfile: file or directory name
"inbox" is not absolute
Most uses of a fileinto action will do the same, unless the user
specifies an absolute path to the desired mailbox file rather than the
plain mailbox name that the sieve specification calls for.
This can be tested as follows, using `docker run --rm -it debian:sid`:
# Install exim
apt-get update
apt-get -y install dialog
apt-get -y install exim4
# Create test user and .forward file
useradd --create-home test
touch /home/test/.forward
chown test.test /home/test/.forward
chmod 0644 /home/test/.forward
# Test 1: Default "keep", should deliver to /var/mail/test but fails
echo '# Sieve filter' > /home/test/.forward
mail test@localhost <<<"Testing"
sleep 1
# Test 2: Relative folder name, should deliver to /home/test/mail/testing but
fails
echo '# Sieve filter' > /home/test/.forward
echo 'require "fileinto";' >> /home/test/.forward
echo 'fileinto "testing";' >> /home/test/.forward
mail test@localhost <<<"Testing 2"
sleep 1
# Test 3: Absolute path, will deliver to /home/test/somefile
echo '# Sieve filter' > /home/test/.forward
echo 'require "fileinto";' >> /home/test/.forward
echo 'fileinto "/home/test/somefile";' >> /home/test/.forward
mail test@localhost <<<"Testing 3"
sleep 1
# Show logs
cat /var/log/exim4/mainlog
Adding the following to the "address_file" transport seems to fix it:
group = mail
file = ${if eq{$address_file}{inbox} \
{/var/mail/$local_part_data} \
{${if eq{${substr_0_1:$address_file}}{/} \
{$address_file} \
{$home/mail/$address_file} \
}} \
}
Or if you'd rather just disable sieve filters by default (so manual
configuration is needed to enable them), you might set
`forbid_sieve_filter` in the "userforward" router.
P.S. README.SIEVE.gz needs updating for the taint change in 4.94-18, it
uses $local_part rather than $local_part_data.
