diff --git a/test/helper/common.bash b/test/helper/common.bash
index a59d7769..1d395351 100644
--- a/test/helper/common.bash
+++ b/test/helper/common.bash
@@ -221,6 +221,7 @@ function _run_until_success_or_timeout() {
 
   local STARTTIME=${SECONDS}
 
+  # shellcheck disable=SC2154
   until run "${@}" && [[ ${status} -eq 0 ]]
   do
     sleep 1
@@ -367,6 +368,7 @@ function _add_mail_account_then_wait_until_ready() {
 #
 # @param ${1} = number of lines that the output should have
 function _should_output_number_of_lines() {
+  # shellcheck disable=SC2154
   assert_equal "${#lines[@]}" "${1:?Number of lines not provided}"
 }
 
diff --git a/test/tests/parallel/set1/spam_virus/amavis.bats b/test/tests/parallel/set1/spam_virus/amavis.bats
index 4211b4c9..18097e69 100644
--- a/test/tests/parallel/set1/spam_virus/amavis.bats
+++ b/test/tests/parallel/set1/spam_virus/amavis.bats
@@ -1,7 +1,7 @@
 load "${REPOSITORY_ROOT}/test/helper/common"
 load "${REPOSITORY_ROOT}/test/helper/setup"
 
-BATS_TEST_NAME_PREFIX='[Amavis] '
+BATS_TEST_NAME_PREFIX='[Amavis + SA] '
 CONTAINER_NAME='dms-test_amavis'
 
 function setup_file() {
@@ -18,10 +18,29 @@ function setup_file() {
 
 function teardown_file() { _default_teardown ; }
 
-@test "SpamAssassin integration should be active" {
+@test 'SpamAssassin integration should be active' {
   # give Amavis just a bit of time to print out its full debug log
   run _repeat_in_container_until_success_or_timeout 5 "${CONTAINER_NAME}" grep 'ANTI-SPAM-SA' /var/log/mail/mail.log
   assert_success
   assert_output --partial 'loaded'
   refute_output --partial 'NOT loaded'
 }
+
+@test 'SA ENV should update Amavis config' {
+  local AMAVIS_DEFAULTS_FILE='/etc/amavis/conf.d/20-debian_defaults'
+  _run_in_container grep '\$sa_tag_level_deflt' "${AMAVIS_DEFAULTS_FILE}"
+  assert_success
+  assert_output --partial '= 2.0'
+
+  _run_in_container grep '\$sa_tag2_level_deflt' "${AMAVIS_DEFAULTS_FILE}"
+  assert_success
+  assert_output --partial '= 6.31'
+
+  _run_in_container grep '\$sa_kill_level_deflt' "${AMAVIS_DEFAULTS_FILE}"
+  assert_success
+  assert_output --partial '= 6.31'
+
+  _run_in_container grep '\$sa_spam_subject_tag' "${AMAVIS_DEFAULTS_FILE}"
+  assert_success
+  assert_output --partial "= '***SPAM*** ';"
+}
diff --git a/test/tests/serial/mail_pop3.bats b/test/tests/serial/mail_pop3.bats
index ab10b19d..c181de79 100644
--- a/test/tests/serial/mail_pop3.bats
+++ b/test/tests/serial/mail_pop3.bats
@@ -1,85 +1,46 @@
-load "${REPOSITORY_ROOT}/test/test_helper/common"
+load "${REPOSITORY_ROOT}/test/helper/common"
+load "${REPOSITORY_ROOT}/test/helper/setup"
+
+BATS_TEST_NAME_PREFIX='[POP3] '
+CONTAINER_NAME='dms-test_pop3'
 
 function setup_file() {
-  local PRIVATE_CONFIG
-  PRIVATE_CONFIG=$(duplicate_config_for_container .)
+  _init_with_defaults
 
-  docker run -d --name mail_pop3 \
-    -v "${PRIVATE_CONFIG}":/tmp/docker-mailserver \
-    -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
-    -e ENABLE_POP3=1 \
-    -e PERMIT_DOCKER=container \
-    -h mail.my-domain.com -t "${NAME}"
+  local CUSTOM_SETUP_ARGUMENTS=(
+    --env ENABLE_POP3=1
+    --env PERMIT_DOCKER=container
+  )
 
-  wait_for_finished_setup_in_container mail_pop3
+  _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
 }
 
-function teardown_file() {
-    docker rm -f mail_pop3
+function teardown_file() { _default_teardown ; }
+
+@test 'server is ready' {
+  _run_in_container nc -w 1 0.0.0.0 110
+  assert_success
+  assert_output --partial '+OK'
 }
 
-#
-# pop
-#
-
-@test "checking pop: server is ready" {
-  run docker exec mail_pop3 /bin/bash -c "nc -w 1 0.0.0.0 110 | grep '+OK'"
+@test 'authentication works' {
+  _run_in_container_bash 'nc -w 1 0.0.0.0 110 < /tmp/docker-mailserver-test/auth/pop3-auth.txt'
   assert_success
 }
 
-@test "checking pop: authentication works" {
-  run docker exec mail_pop3 /bin/sh -c "nc -w 1 0.0.0.0 110 < /tmp/docker-mailserver-test/auth/pop3-auth.txt"
+@test 'added user authentication works' {
+  _run_in_container_bash 'nc -w 1 0.0.0.0 110 < /tmp/docker-mailserver-test/auth/added-pop3-auth.txt'
   assert_success
 }
 
-@test "checking pop: added user authentication works" {
-  run docker exec mail_pop3 /bin/sh -c "nc -w 1 0.0.0.0 110 < /tmp/docker-mailserver-test/auth/added-pop3-auth.txt"
-  assert_success
-}
-
-#
-# spamassassin
-#
-
-@test "checking spamassassin: docker env variables are set correctly (default)" {
-  run docker exec mail_pop3 /bin/sh -c "grep '\$sa_tag_level_deflt' /etc/amavis/conf.d/20-debian_defaults | grep '= 2.0'"
-  assert_success
-
-  run docker exec mail_pop3 /bin/sh -c "grep '\$sa_tag2_level_deflt' /etc/amavis/conf.d/20-debian_defaults | grep '= 6.31'"
-  assert_success
-
-  run docker exec mail_pop3 /bin/sh -c "grep '\$sa_kill_level_deflt' /etc/amavis/conf.d/20-debian_defaults | grep '= 6.31'"
-  assert_success
-
-  run docker exec mail_pop3 /bin/sh -c "grep '\$sa_spam_subject_tag' /etc/amavis/conf.d/20-debian_defaults | grep '= .\*\*\*SPAM\*\*\* .'"
-  assert_success
-}
-
-#
-# system
-#
-
-@test "checking system: /var/log/mail/mail.log is error free" {
-  run docker exec mail_pop3 grep 'non-null host address bits in' /var/log/mail/mail.log
+@test '/var/log/mail/mail.log is error-free' {
+  _run_in_container grep 'non-null host address bits in' /var/log/mail/mail.log
   assert_failure
-
-  run docker exec mail_pop3 grep ': error:' /var/log/mail/mail.log
+  _run_in_container grep ': error:' /var/log/mail/mail.log
   assert_failure
 }
 
-#
-# sieve
-#
-
-@test "checking manage sieve: disabled per default" {
-  run docker exec mail_pop3 /bin/bash -c "nc -z 0.0.0.0 4190"
+@test '(Manage Sieve) disabled per default' {
+  _run_in_container nc -z 0.0.0.0 4190
   assert_failure
 }
-
-#
-# PERMIT_DOCKER mynetworks
-#
-@test "checking PERMIT_DOCKER: my network value" {
-  run docker exec mail_pop3 /bin/sh -c "postconf | grep '^mynetworks =' | egrep '[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}\.[[:digit:]]{1,3}/32'"
-  assert_success
-}
diff --git a/test/tests/serial/mail_with_imap.bats b/test/tests/serial/mail_with_imap.bats
index 1b3d54d5..6225ff36 100644
--- a/test/tests/serial/mail_with_imap.bats
+++ b/test/tests/serial/mail_with_imap.bats
@@ -1,49 +1,42 @@
-load "${REPOSITORY_ROOT}/test/test_helper/common"
+load "${REPOSITORY_ROOT}/test/helper/common"
+load "${REPOSITORY_ROOT}/test/helper/setup"
 
-setup_file() {
-  local PRIVATE_CONFIG
-  PRIVATE_CONFIG=$(duplicate_config_for_container .)
+BATS_TEST_NAME_PREFIX='[SASLauthd + RIMAP] '
+CONTAINER_NAME='dms-test_saslauthd_and_rimap'
 
-  docker run -d --name mail_with_imap \
-    -v "${PRIVATE_CONFIG}":/tmp/docker-mailserver \
-    -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
-    -e ENABLE_SASLAUTHD=1 \
-    -e POSTMASTER_ADDRESS=postmaster@localhost.localdomain \
-    -e SASLAUTHD_MECH_OPTIONS=127.0.0.1 \
-    -e SASLAUTHD_MECHANISMS=rimap \
-    -e PERMIT_DOCKER=container \
-    -h mail.my-domain.com -t "${NAME}"
+function setup_file() {
+  _init_with_defaults
 
-  wait_for_smtp_port_in_container mail_with_imap
+  local CUSTOM_SETUP_ARGUMENTS=(
+    --env ENABLE_SASLAUTHD=1
+    --env SASLAUTHD_MECH_OPTIONS=127.0.0.1
+    --env SASLAUTHD_MECHANISMS=rimap
+    --env PERMIT_DOCKER=container
+  )
+
+  _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
+  _wait_for_smtp_port_in_container mail_with_imap
 }
 
-teardown_file() {
-  docker rm -f mail_with_imap
-}
+function teardown_file() { _default_teardown ; }
 
-#
-# RIMAP
-#
-
-# dovecot
-@test "checking dovecot: ldap rimap connection and authentication works" {
-  run docker exec mail_with_imap /bin/sh -c "nc -w 1 0.0.0.0 143 < /tmp/docker-mailserver-test/auth/imap-auth.txt"
+@test '(Dovecot) LDAP RIMAP connection and authentication works' {
+  _run_in_container_bash "nc -w 1 0.0.0.0 143 < /tmp/docker-mailserver-test/auth/imap-auth.txt"
   assert_success
 }
 
-# saslauthd
-@test "checking saslauthd: sasl rimap authentication works" {
-  run docker exec mail_with_imap bash -c "testsaslauthd -u user1@localhost.localdomain -p mypassword"
+@test '(SASLauthd) SASL RIMAP authentication works' {
+  _run_in_container testsaslauthd -u 'user1@localhost.localdomain' -p 'mypassword'
   assert_success
 }
 
-@test "checking saslauthd: rimap smtp authentication" {
-  run docker exec mail_with_imap /bin/sh -c "nc -w 5 0.0.0.0 25 < /tmp/docker-mailserver-test/auth/smtp-auth-login.txt | grep 'Authentication successful'"
+@test '(SASLauthd) RIMAP SMTP authentication works' {
+  _run_in_container_bash 'nc -w 5 0.0.0.0 25 < /tmp/docker-mailserver-test/auth/smtp-auth-login.txt'
   assert_success
+  assert_output --partial 'Authentication successful'
 }
 
-# master account
-@test "checking dovecot: master account can login" {
-  run docker exec mail_with_imap bash -c "testsaslauthd -u user1@localhost.localdomain*masterusername -p masterpassword"
+@test '(Dovecot) master account can login' {
+  _run_in_container testsaslauthd -u 'user1@localhost.localdomain*masterusername' -p 'masterpassword'
   assert_success
 }
diff --git a/test/tests/serial/mail_with_relays.bats b/test/tests/serial/mail_with_relays.bats
index ae42d812..066e9fcf 100644
--- a/test/tests/serial/mail_with_relays.bats
+++ b/test/tests/serial/mail_with_relays.bats
@@ -1,81 +1,84 @@
-load "${REPOSITORY_ROOT}/test/test_helper/common"
+load "${REPOSITORY_ROOT}/test/helper/common"
+load "${REPOSITORY_ROOT}/test/helper/setup"
+
+BATS_TEST_NAME_PREFIX='[Relay Host] '
+CONTAINER_NAME='dms-test_relay'
 
 function setup_file() {
-  # We use a temporary config directory since we'll be dynamically editing
-  # it with setup.sh.
-  tmp_confdir=$(mktemp -d /tmp/docker-mailserver-config-relay-hosts-XXXXX)
-  cp -a test/config/relay-hosts/* "${tmp_confdir}/"
+  _init_with_defaults
 
-  docker run -d --name mail_with_relays \
-    -v "${tmp_confdir}":/tmp/docker-mailserver \
-    -v "$(pwd)/test/test-files":/tmp/docker-mailserver-test:ro \
-    -e RELAY_HOST=default.relay.com \
-    -e RELAY_PORT=2525 \
-    -e RELAY_USER=smtp_user \
-    -e RELAY_PASSWORD=smtp_password \
-    -e PERMIT_DOCKER=host \
-    -h mail.my-domain.com -t "${NAME}"
+  mv "${TEST_TMP_CONFIG}/relay-hosts/"* "${TEST_TMP_CONFIG}/"
 
-  wait_for_finished_setup_in_container mail_with_relays
+  local CUSTOM_SETUP_ARGUMENTS=(
+    --env RELAY_HOST=default.relay.com
+    --env RELAY_PORT=2525
+    --env RELAY_USER=smtp_user
+    --env RELAY_PASSWORD=smtp_password
+    --env PERMIT_DOCKER=host
+  )
+
+  _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
 }
 
-function teardown_file() {
-  docker rm -f mail_with_relays
-  rm -rf "${tmp_confdir}"
+function teardown_file() { _default_teardown ; }
+
+@test 'default mapping is added from ENV variables' {
+  _run_in_container grep 'domainone.tld' /etc/postfix/relayhost_map
+  assert_success
+  assert_output --regexp '^@domainone.tld[[:space:]]+\[default.relay.com\]:2525$'
 }
 
-@test "checking relay hosts: default mapping is added from env vars" {
-  run docker exec mail_with_relays grep -e domainone.tld /etc/postfix/relayhost_map
-  assert_output -e '^@domainone.tld[[:space:]]+\[default.relay.com\]:2525$'
+@test 'default mapping is added from ENV variables for virtual user entry' {
+  _run_in_container grep 'domain1.tld' /etc/postfix/relayhost_map
+  assert_success
+  assert_output --regexp '^@domain1.tld[[:space:]]+\[default.relay.com\]:2525$'
 }
 
-@test "checking relay hosts: default mapping is added from env vars for virtual user entry" {
-  run docker exec mail_with_relays grep -e domain1.tld /etc/postfix/relayhost_map
-  assert_output -e '^@domain1.tld[[:space:]]+\[default.relay.com\]:2525$'
+@test 'default mapping is added from ENV variables for new user entry' {
+  _run_in_container grep 'domainzero.tld' /etc/postfix/relayhost_map
+  assert_failure
+
+  _add_mail_account_then_wait_until_ready 'user0@domainzero.tld' 'password123'
+  _run_until_success_or_timeout 20 _exec_in_container grep 'domainzero.tld' /etc/postfix/relayhost_map
+  assert_success
+  assert_output --regexp '^@domainzero.tld[[:space:]]+\[default.relay.com\]:2525$'
 }
 
-@test "checking relay hosts: default mapping is added from env vars for new user entry" {
-  run docker exec mail_with_relays grep -e domainzero.tld /etc/postfix/relayhost_map
-  assert_output ''
+@test 'default mapping is added from ENV variables for new virtual user (alias) entry' {
+  _run_in_container grep 'domain2.tld' /etc/postfix/relayhost_map
+  assert_failure
 
-  run ./setup.sh -c mail_with_relays email add user0@domainzero.tld password123
-  run_until_success_or_timeout 10 docker exec mail_with_relays grep -e domainzero.tld /etc/postfix/relayhost_map
-  assert_output -e '^@domainzero.tld[[:space:]]+\[default.relay.com\]:2525$'
+  run ./setup.sh -c "${CONTAINER_NAME}" alias add 'user2@domain2.tld' 'user2@domaintwo.tld'
+  assert_success
+  _run_until_success_or_timeout 10 _exec_in_container grep 'domain2.tld' /etc/postfix/relayhost_map
+  assert_success
+  assert_output --regexp '^@domain2.tld[[:space:]]+\[default.relay.com\]:2525$'
 }
 
-@test "checking relay hosts: default mapping is added from env vars for new virtual user entry" {
-  run docker exec mail_with_relays grep -e domain2.tld /etc/postfix/relayhost_map
-  assert_output ''
-
-  run ./setup.sh -c mail_with_relays alias add user2@domain2.tld user2@domaintwo.tld
-  run_until_success_or_timeout 10 docker exec mail_with_relays grep -e domain2.tld /etc/postfix/relayhost_map
-  assert_output -e '^@domain2.tld[[:space:]]+\[default.relay.com\]:2525$'
+@test 'custom mapping is added from file' {
+  _run_in_container grep 'domaintwo.tld' /etc/postfix/relayhost_map
+  assert_success
+  assert_output --regexp '^@domaintwo.tld[[:space:]]+\[other.relay.com\]:587$'
 }
 
-@test "checking relay hosts: custom mapping is added from file" {
-  run docker exec mail_with_relays grep -e domaintwo.tld /etc/postfix/relayhost_map
-  assert_output -e '^@domaintwo.tld[[:space:]]+\[other.relay.com\]:587$'
+@test 'ignored domain is not added' {
+  _run_in_container grep domainthree.tld /etc/postfix/relayhost_map
+  assert_failure
 }
 
-@test "checking relay hosts: ignored domain is not added" {
-  run docker exec mail_with_relays grep -e domainthree.tld /etc/postfix/relayhost_map
-  assert_failure 1
-  assert_output ''
-}
-
-@test "checking relay hosts: sasl_passwd exists" {
-  run docker exec mail_with_relays [ -f /etc/postfix/sasl_passwd ]
+@test '/etc/postfix/sasl_passwd exists' {
+  _run_in_container_bash '[[ -f /etc/postfix/sasl_passwd ]]'
   assert_success
 }
 
-@test "checking relay hosts: auth entry is added" {
-  run docker exec mail_with_relays /bin/sh -c 'cat /etc/postfix/sasl_passwd | grep -e "^@domaintwo.tld\s\+smtp_user_2:smtp_password_2" | wc -l'
+@test 'auth entry is added' {
+  _run_in_container grep '^@domaintwo.tld\s\+smtp_user_2:smtp_password_2' /etc/postfix/sasl_passwd
   assert_success
-  assert_output 1
+  _should_output_number_of_lines 1
 }
 
-@test "checking relay hosts: default auth entry is added" {
-  run docker exec mail_with_relays /bin/sh -c 'cat /etc/postfix/sasl_passwd | grep -e "^\[default.relay.com\]:2525\s\+smtp_user:smtp_password" | wc -l'
+@test 'default auth entry is added' {
+  _run_in_container grep '^\[default.relay.com\]:2525\s\+smtp_user:smtp_password' /etc/postfix/sasl_passwd
   assert_success
-  assert_output 1
+  _should_output_number_of_lines 1
 }
diff --git a/test/tests/serial/no_container.bats b/test/tests/serial/no_container.bats
index 16512527..c443bd62 100644
--- a/test/tests/serial/no_container.bats
+++ b/test/tests/serial/no_container.bats
@@ -8,10 +8,10 @@ load "${REPOSITORY_ROOT}/test/helper/common"
 BATS_TEST_NAME_PREFIX='[No Existing Container] '
 
 function setup_file() {
-  # Fail early if the testing image is already running:
-  assert_not_equal "$(docker ps | grep -o "${IMAGE_NAME}")" "${IMAGE_NAME}"
+  run docker ps # fail early if the testing image is already running:
+  assert_success
+  refute_output --partial "${IMAGE_NAME}"
 
-  # Copy the base config that `setup.sh` will volume mount to a container it runs:
   export TEST_TMP_CONFIG
   TEST_TMP_CONFIG=$(_duplicate_config_for_container . 'no_container')
 }