From ae05e6a7c379825fb464a648acc04b4074dd547f Mon Sep 17 00:00:00 2001
From: Georg Lauterbach <44545919+georglauterbach@users.noreply.github.com>
Date: Fri, 24 Feb 2023 10:44:18 +0100
Subject: [PATCH] tests: improve `_send_email` (#3105)

---
 test/helper/common.bash                       |  2 +-
 test/helper/sending.bash                      | 36 +++++++----
 .../parallel/set1/dovecot/dovecot_sieve.bats  |  4 +-
 .../set1/dovecot/mailbox_format_dbox.bats     |  4 +-
 .../set1/dovecot/special_use_folders.bats     |  5 +-
 .../parallel/set1/spam_virus/amavis.bats      |  4 +-
 .../parallel/set1/spam_virus/clamav.bats      |  2 +-
 .../disabled_clamav_spamassassin.bats         |  2 +-
 .../parallel/set1/spam_virus/fail2ban.bats    |  4 +-
 .../parallel/set1/spam_virus/postscreen.bats  |  7 +--
 .../parallel/set1/spam_virus/rspamd.bats      |  6 +-
 .../set1/spam_virus/spam_junk_folder.bats     |  2 +-
 .../container_configuration/hostname.bats     |  2 +-
 test/tests/parallel/set3/mta/lmtp_ip.bats     |  2 +-
 .../parallel/set3/mta/smtp_delivery.bats      | 61 ++++++++-----------
 test/tests/parallel/set3/mta/smtponly.bats    |  2 +-
 test/tests/serial/mail_pop3.bats              |  6 +-
 test/tests/serial/mail_with_imap.bats         | 14 ++---
 test/tests/serial/tests.bats                  | 16 ++---
 19 files changed, 88 insertions(+), 93 deletions(-)

diff --git a/test/helper/common.bash b/test/helper/common.bash
index 09e0b9f1..6920828b 100644
--- a/test/helper/common.bash
+++ b/test/helper/common.bash
@@ -468,7 +468,7 @@ function _service_log_should_contain_string() {
 
 # Filters the mail log for lines that belong to a certain email identified
 # by its ID. You can obtain the ID of an email you want to send by using
-# `_send_mail_and_get_id`.
+# `_send_email_and_get_id`.
 #
 # @param ${1} = email ID
 # @param ${2} = container name [OPTIONAL]
diff --git a/test/helper/sending.bash b/test/helper/sending.bash
index 29a45622..631617a1 100644
--- a/test/helper/sending.bash
+++ b/test/helper/sending.bash
@@ -7,25 +7,29 @@
 # ! ATTENTION: This file is loaded by `common.sh` - do not load it yourself!
 # ! ATTENTION: This file requires helper functions from `common.sh`!
 
-# Sends a mail from localhost (127.0.0.1) via port 25 to the container. To send
-# a custom email, create a file at `test/test-files/email-templates/<TEST FILE>`,
+# Sends a mail from localhost (127.0.0.1) to a container. To send
+# a custom email, create a file at `test/test-files/<TEST FILE>`,
 # and provide `<TEST FILE>` as an argument to this function.
 #
 # @param ${1} = template file (path) name
-# @param ${2} = container name [OPTIONAL]
-# @param ${3} = port `nc` will use [OPTIONAL]
+# @param ${2} = parameters for `nc` [OPTIONAL] (default: `0.0.0.0 25`)
 #
 # ## Attention
 #
+# This function assumes `CONTAINER_NAME` to be properly set (to the container
+# name the command should be executed in)!
+#
 # This function will just send the email in an "asynchronous" fashion, i.e. it will
 # send the email but it will not make sure the mail queue is empty after the mail
 # has been sent.
 function _send_email() {
   local TEMPLATE_FILE=${1:?Must provide name of template file}
-  local CONTAINER_NAME=$(__handle_container_name "${2:-}")
-  local PORT=${3:-25}
+  local NC_PARAMETERS=${2:-0.0.0.0 25}
 
-  _run_in_container_bash "nc 0.0.0.0 ${PORT} < /tmp/docker-mailserver-test/email-templates/${TEMPLATE_FILE}.txt"
+  assert_not_equal "${NC_PARAMETERS}" ''
+  assert_not_equal "${CONTAINER_NAME:-}" ''
+
+  _run_in_container_bash "nc ${NC_PARAMETERS} < /tmp/docker-mailserver-test/${TEMPLATE_FILE}.txt"
   assert_success
 }
 
@@ -39,7 +43,12 @@ function _send_email() {
 # test file and need to assert certain log entries for each mail individually.
 #
 # @param ${1} = template file (path) name
-# @param ${2} = container name [OPTIONAL]
+# @param ${2} = parameters for `nc` [OPTIONAL] (default: `0.0.0.0 25`)
+#
+# ## Attention
+#
+# This function assumes `CONTAINER_NAME` to be properly set (to the container
+# name the command should be executed in)!
 #
 # ## Safety
 #
@@ -47,11 +56,14 @@ function _send_email() {
 # If two clients send simultaneously, there is no guarantee the correct ID is
 # chosen. Sending more than one mail at any given point in time with this function
 # is UNDEFINED BEHAVIOR!
-function _send_mail_and_get_id() {
+function _send_email_and_get_id() {
   local TEMPLATE_FILE=${1:?Must provide name of template file}
-  local CONTAINER_NAME=$(__handle_container_name "${2:-}")
+  local NC_PARAMETERS=${2:-0.0.0.0 25}
   local MAIL_ID
 
+  assert_not_equal "${NC_PARAMETERS}" ''
+  assert_not_equal "${CONTAINER_NAME:-}" ''
+
   _wait_for_empty_mail_queue_in_container
   _send_email "${TEMPLATE_FILE}"
   _wait_for_empty_mail_queue_in_container
@@ -63,8 +75,6 @@ function _send_mail_and_get_id() {
     | grep -E -m 1 'postfix/smtpd.*: [A-Z0-9]+: client=localhost' \
     | grep -E -o '[A-Z0-9]{9,12}' || true)
 
-  run bash -c "-z ${MAIL_ID}"
-  assert_success 'Could not obtain mail ID - aborting!'
-
+  assert_not_equal "${MAIL_ID}" ''
   echo "${MAIL_ID}"
 }
diff --git a/test/tests/parallel/set1/dovecot/dovecot_sieve.bats b/test/tests/parallel/set1/dovecot/dovecot_sieve.bats
index 9e80932b..889890d2 100644
--- a/test/tests/parallel/set1/dovecot/dovecot_sieve.bats
+++ b/test/tests/parallel/set1/dovecot/dovecot_sieve.bats
@@ -26,9 +26,9 @@ function setup_file() {
   _wait_for_smtp_port_in_container
 
   # Single mail sent from 'spam@spam.com' that is handled by User (relocate) and Global (copy) sieves for user1:
-  _send_email 'sieve-spam-folder'
+  _send_email 'email-templates/sieve-spam-folder'
   # Mail for user2 triggers the sieve-pipe:
-  _send_email 'sieve-pipe'
+  _send_email 'email-templates/sieve-pipe'
 
   _wait_for_empty_mail_queue_in_container
 }
diff --git a/test/tests/parallel/set1/dovecot/mailbox_format_dbox.bats b/test/tests/parallel/set1/dovecot/mailbox_format_dbox.bats
index 61db93dc..8ce03d9a 100644
--- a/test/tests/parallel/set1/dovecot/mailbox_format_dbox.bats
+++ b/test/tests/parallel/set1/dovecot/mailbox_format_dbox.bats
@@ -26,7 +26,7 @@ function teardown() { _default_teardown ; }
   _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
   _wait_for_smtp_port_in_container
 
-  _send_email 'existing-user1'
+  _send_email 'email-templates/existing-user1'
   _wait_for_empty_mail_queue_in_container
 
   # Mail received should be stored as `u.1` (one file per message)
@@ -47,7 +47,7 @@ function teardown() { _default_teardown ; }
   _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
   _wait_for_smtp_port_in_container
 
-  _send_email 'existing-user1'
+  _send_email 'email-templates/existing-user1'
   _wait_for_empty_mail_queue_in_container
 
   # Mail received should be stored in `m.1` (1 or more messages)
diff --git a/test/tests/parallel/set1/dovecot/special_use_folders.bats b/test/tests/parallel/set1/dovecot/special_use_folders.bats
index 69db014d..e70899a0 100644
--- a/test/tests/parallel/set1/dovecot/special_use_folders.bats
+++ b/test/tests/parallel/set1/dovecot/special_use_folders.bats
@@ -14,7 +14,7 @@ function setup_file() {
 function teardown_file() { _default_teardown ; }
 
 @test 'normal delivery works' {
-  _send_email 'existing-user1'
+  _send_email 'email-templates/existing-user1'
   _count_files_in_directory_in_container /var/mail/localhost.localdomain/user1/new 1
 }
 
@@ -26,8 +26,7 @@ function teardown_file() { _default_teardown ; }
 }
 
 @test "(IMAP) special-use folders should be created when necessary" {
-  _run_in_container_bash "nc -w 8 0.0.0.0 143 < /tmp/docker-mailserver-test/nc_templates/imap_special_use_folders.txt"
-  assert_success
+  _send_email 'nc_templates/imap_special_use_folders' '-w 8 0.0.0.0 143'
   assert_output --partial 'Drafts'
   assert_output --partial 'Junk'
   assert_output --partial 'Trash'
diff --git a/test/tests/parallel/set1/spam_virus/amavis.bats b/test/tests/parallel/set1/spam_virus/amavis.bats
index c687a70c..875127b1 100644
--- a/test/tests/parallel/set1/spam_virus/amavis.bats
+++ b/test/tests/parallel/set1/spam_virus/amavis.bats
@@ -26,7 +26,9 @@ function setup_file() {
   _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
 }
 
-function teardown_file() { _default_teardown ; }
+function teardown_file() {
+  docker rm -f "${CONTAINER1_NAME}" "${CONTAINER2_NAME}"
+}
 
 @test '(Amavis enabled) configuration should be correct' {
   export CONTAINER_NAME=${CONTAINER1_NAME}
diff --git a/test/tests/parallel/set1/spam_virus/clamav.bats b/test/tests/parallel/set1/spam_virus/clamav.bats
index e80c3068..31608ef8 100644
--- a/test/tests/parallel/set1/spam_virus/clamav.bats
+++ b/test/tests/parallel/set1/spam_virus/clamav.bats
@@ -25,7 +25,7 @@ function setup_file() {
 
   _wait_for_service postfix
   _wait_for_smtp_port_in_container
-  _send_email 'amavis-virus'
+  _send_email 'email-templates/amavis-virus'
   _wait_for_empty_mail_queue_in_container
 }
 
diff --git a/test/tests/parallel/set1/spam_virus/disabled_clamav_spamassassin.bats b/test/tests/parallel/set1/spam_virus/disabled_clamav_spamassassin.bats
index e639950b..8402422c 100644
--- a/test/tests/parallel/set1/spam_virus/disabled_clamav_spamassassin.bats
+++ b/test/tests/parallel/set1/spam_virus/disabled_clamav_spamassassin.bats
@@ -17,7 +17,7 @@ function setup_file() {
   _common_container_setup 'CUSTOM_SETUP_ARGUMENTS'
   _wait_for_smtp_port_in_container
 
-  _send_email 'existing-user1'
+  _send_email 'email-templates/existing-user1'
   _wait_for_empty_mail_queue_in_container
 }
 
diff --git a/test/tests/parallel/set1/spam_virus/fail2ban.bats b/test/tests/parallel/set1/spam_virus/fail2ban.bats
index 262e4e21..8ce843fc 100644
--- a/test/tests/parallel/set1/spam_virus/fail2ban.bats
+++ b/test/tests/parallel/set1/spam_virus/fail2ban.bats
@@ -74,8 +74,8 @@ function teardown_file() {
 @test "ban ip on multiple failed login" {
   CONTAINER1_IP=$(_get_container_ip "${CONTAINER1_NAME}")
   # Trigger a ban by failing to login twice:
-  _run_in_container_explicit "${CONTAINER2_NAME}" bash -c "nc ${CONTAINER1_IP} 465 < /tmp/docker-mailserver-test/auth/smtp-auth-login-wrong.txt"
-  _run_in_container_explicit "${CONTAINER2_NAME}" bash -c "nc ${CONTAINER1_IP} 465 < /tmp/docker-mailserver-test/auth/smtp-auth-login-wrong.txt"
+  CONTAINER_NAME=${CONTAINER2_NAME} _send_email 'auth/smtp-auth-login-wrong' "${CONTAINER1_IP} 465"
+  CONTAINER_NAME=${CONTAINER2_NAME} _send_email 'auth/smtp-auth-login-wrong' "${CONTAINER1_IP} 465"
 
   # Checking that CONTAINER2_IP is banned in "${CONTAINER1_NAME}"
   CONTAINER2_IP=$(_get_container_ip "${CONTAINER2_NAME}")
diff --git a/test/tests/parallel/set1/spam_virus/postscreen.bats b/test/tests/parallel/set1/spam_virus/postscreen.bats
index 4121e1f8..240ba58a 100644
--- a/test/tests/parallel/set1/spam_virus/postscreen.bats
+++ b/test/tests/parallel/set1/spam_virus/postscreen.bats
@@ -37,9 +37,8 @@ function teardown_file() {
   docker rm -f "${CONTAINER1_NAME}" "${CONTAINER2_NAME}"
 }
 
-@test "should fail send when talking out of turn" {
-  _run_in_container_explicit "${CONTAINER2_NAME}" bash -c "nc ${CONTAINER1_IP} 25 < /tmp/docker-mailserver-test/email-templates/postscreen.txt"
-  assert_success
+@test 'should fail send when talking out of turn' {
+  CONTAINER_NAME=${CONTAINER2_NAME} _send_email 'email-templates/postscreen' "${CONTAINER1_IP} 25"
   assert_output --partial 'Protocol error'
 
   # Expected postscreen log entry:
@@ -62,7 +61,7 @@ function teardown_file() {
 }
 
 # When postscreen is active, it prevents the usual method of piping a file through nc:
-# (Won't work: _run_in_container_explicit "${CLIENT_CONTAINER_NAME}" bash -c "nc ${TARGET_CONTAINER_IP} 25 < ${SMTP_TEMPLATE}")
+# (Won't work: CONTAINER_NAME=${CLIENT_CONTAINER_NAME} _send_email "${SMTP_TEMPLATE}" "${TARGET_CONTAINER_IP} 25")
 # The below workaround respects `postscreen_greet_wait` time (default 6 sec), talking to the mail-server in turn:
 # https://www.postfix.org/postconf.5.html#postscreen_greet_wait
 function _should_wait_turn_speaking_smtp() {
diff --git a/test/tests/parallel/set1/spam_virus/rspamd.bats b/test/tests/parallel/set1/spam_virus/rspamd.bats
index 19ffe6e2..96137b3d 100644
--- a/test/tests/parallel/set1/spam_virus/rspamd.bats
+++ b/test/tests/parallel/set1/spam_virus/rspamd.bats
@@ -31,9 +31,9 @@ function setup_file() {
 
   # We will send 3 emails: the first one should pass just fine; the second one should
   # be rejected due to spam; the third one should be rejected due to a virus.
-  export MAIL_ID1=$(_send_mail_and_get_id 'existing-user1')
-  export MAIL_ID2=$(_send_mail_and_get_id 'rspamd-spam')
-  export MAIL_ID3=$(_send_mail_and_get_id 'rspamd-virus')
+  export MAIL_ID1=$(_send_email_and_get_id 'email-templates/existing-user1')
+  export MAIL_ID2=$(_send_email_and_get_id 'email-templates/rspamd-spam')
+  export MAIL_ID3=$(_send_email_and_get_id 'email-templates/rspamd-virus')
 
   # add a nested option to a module
   _exec_in_container_bash "echo -e 'complicated {\n    anOption = someValue;\n}' >/etc/rspamd/override.d/testmodule_complicated.conf"
diff --git a/test/tests/parallel/set1/spam_virus/spam_junk_folder.bats b/test/tests/parallel/set1/spam_virus/spam_junk_folder.bats
index 7a1bf609..237218e8 100644
--- a/test/tests/parallel/set1/spam_virus/spam_junk_folder.bats
+++ b/test/tests/parallel/set1/spam_virus/spam_junk_folder.bats
@@ -72,7 +72,7 @@ function teardown() { _default_teardown ; }
 function _should_send_spam_message() {
   _wait_for_smtp_port_in_container
   _wait_for_tcp_port_in_container 10024 # port 10024 is for Amavis
-  _send_email 'amavis-spam'
+  _send_email 'email-templates/amavis-spam'
 }
 
 function _should_be_received_by_amavis() {
diff --git a/test/tests/parallel/set3/container_configuration/hostname.bats b/test/tests/parallel/set3/container_configuration/hostname.bats
index cede4bca..98a98851 100644
--- a/test/tests/parallel/set3/container_configuration/hostname.bats
+++ b/test/tests/parallel/set3/container_configuration/hostname.bats
@@ -206,7 +206,7 @@ function _should_have_correct_mail_headers() {
   # (eg: OVERRIDE_HOSTNAME or `--hostname mail --domainname example.test`)
   local EXPECTED_HOSTNAME=${3:-${EXPECTED_FQDN}}
 
-  _send_email 'existing-user1'
+  _send_email 'email-templates/existing-user1'
   _wait_for_empty_mail_queue_in_container
   _count_files_in_directory_in_container '/var/mail/localhost.localdomain/user1/new/' '1'
 
diff --git a/test/tests/parallel/set3/mta/lmtp_ip.bats b/test/tests/parallel/set3/mta/lmtp_ip.bats
index ae74001b..861f7f60 100644
--- a/test/tests/parallel/set3/mta/lmtp_ip.bats
+++ b/test/tests/parallel/set3/mta/lmtp_ip.bats
@@ -38,7 +38,7 @@ function teardown_file() { _default_teardown ; }
 
 @test "delivers mail to existing account" {
   _wait_for_smtp_port_in_container
-  _send_email 'existing-user1' # send a test email
+  _send_email 'email-templates/existing-user1' # send a test email
 
   # Verify delivery was successful, log line should look similar to:
   # postfix/lmtp[1274]: 0EA424ABE7D9: to=<user1@localhost.localdomain>, relay=127.0.0.1[127.0.0.1]:24, delay=0.13, delays=0.07/0.01/0.01/0.05, dsn=2.0.0, status=sent (250 2.0.0 <user1@localhost.localdomain> ixPpB+Zvv2P7BAAAUi6ngw Saved)
diff --git a/test/tests/parallel/set3/mta/smtp_delivery.bats b/test/tests/parallel/set3/mta/smtp_delivery.bats
index df66debe..af98b2f4 100644
--- a/test/tests/parallel/set3/mta/smtp_delivery.bats
+++ b/test/tests/parallel/set3/mta/smtp_delivery.bats
@@ -55,40 +55,41 @@ function setup_file() {
   _wait_for_tcp_port_in_container 10024
   _wait_for_smtp_port_in_container_to_respond
 
+  # see https://github.com/docker-mailserver/docker-mailserver/pull/3105#issuecomment-1441055103
   # Amavis may still not be ready to receive mail, sleep a little to avoid connection failures:
-  sleep 1
+  sleep 5
 
   ### Send mail to queue for delivery ###
 
   # TODO: Move to clamav tests (For use when ClamAV is enabled):
   # _repeat_in_container_until_success_or_timeout 60 "${CONTAINER_NAME}" test -e /var/run/clamav/clamd.ctl
-  # _run_in_container_bash "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/amavis-virus.txt"
+  # _send_email 'email-templates/amavis-virus'
 
   # Required for 'delivers mail to existing alias':
-  _send_email 'existing-alias-external'
+  _send_email 'email-templates/existing-alias-external'
   # Required for 'delivers mail to existing alias with recipient delimiter':
-  _send_email 'existing-alias-recipient-delimiter'
+  _send_email 'email-templates/existing-alias-recipient-delimiter'
   # Required for 'delivers mail to existing catchall':
-  _send_email 'existing-catchall-local'
+  _send_email 'email-templates/existing-catchall-local'
   # Required for 'delivers mail to regexp alias':
-  _send_email 'existing-regexp-alias-local'
+  _send_email 'email-templates/existing-regexp-alias-local'
 
   # Required for 'rejects mail to unknown user':
-  _send_email 'non-existing-user'
+  _send_email 'email-templates/non-existing-user'
   # Required for 'redirects mail to external aliases':
-  _send_email 'existing-regexp-alias-external'
-  _send_email 'existing-alias-local'
+  _send_email 'email-templates/existing-regexp-alias-external'
+  _send_email 'email-templates/existing-alias-local'
   # Required for 'rejects spam':
-  _send_email 'amavis-spam'
+  _send_email 'email-templates/amavis-spam'
 
   # Required for 'delivers mail to existing account':
-  _send_email 'existing-user1'
-  _send_email 'existing-user2'
-  _send_email 'existing-user3'
-  _send_email 'existing-added'
-  _send_email 'existing-user-and-cc-local-alias'
-  _send_email 'sieve-spam-folder'
-  _send_email 'sieve-pipe'
+  _send_email 'email-templates/existing-user1'
+  _send_email 'email-templates/existing-user2'
+  _send_email 'email-templates/existing-user3'
+  _send_email 'email-templates/existing-added'
+  _send_email 'email-templates/existing-user-and-cc-local-alias'
+  _send_email 'email-templates/sieve-spam-folder'
+  _send_email 'email-templates/sieve-pipe'
   _run_in_container_bash 'sendmail root < /tmp/docker-mailserver-test/email-templates/root-email.txt'
 }
 
@@ -102,50 +103,43 @@ function setup_file() {
 }
 
 @test "should successfully authenticate with good password (plain)" {
-  _run_in_container_bash 'nc -w 5 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/smtp-auth-plain.txt'
-  assert_success
+  _send_email 'auth/smtp-auth-plain' '-w 5 0.0.0.0 465'
   assert_output --partial 'Authentication successful'
 }
 
 @test "should fail to authenticate with wrong password (plain)" {
-  _run_in_container_bash 'nc -w 20 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/smtp-auth-plain-wrong.txt'
+  _send_email 'auth/smtp-auth-plain-wrong' '-w 20 0.0.0.0 465'
   assert_output --partial 'authentication failed'
-  assert_success
 }
 
 @test "should successfully authenticate with good password (login)" {
-  _run_in_container_bash 'nc -w 5 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/smtp-auth-login.txt'
-  assert_success
+  _send_email 'auth/smtp-auth-login' '-w 5 0.0.0.0 465'
   assert_output --partial 'Authentication successful'
 }
 
 @test "should fail to authenticate with wrong password (login)" {
-  _run_in_container_bash 'nc -w 20 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/smtp-auth-login-wrong.txt'
+  _send_email 'auth/smtp-auth-login-wrong' '-w 20 0.0.0.0 465'
   assert_output --partial 'authentication failed'
-  assert_success
 }
 
 @test "[user: 'added'] should successfully authenticate with good password (plain)" {
-  _run_in_container_bash 'nc -w 5 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/added-smtp-auth-plain.txt'
-  assert_success
+  _send_email 'auth/added-smtp-auth-plain' '-w 5 0.0.0.0 465'
   assert_output --partial 'Authentication successful'
 }
 
 @test "[user: 'added'] should fail to authenticate with wrong password (plain)" {
-  _run_in_container_bash 'nc -w 20 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/added-smtp-auth-plain-wrong.txt'
-  assert_success
+  _send_email 'auth/added-smtp-auth-plain-wrong' '-w 20 0.0.0.0 465'
   assert_output --partial 'authentication failed'
 }
 
 @test "[user: 'added'] should successfully authenticate with good password (login)" {
-  _run_in_container_bash 'nc -w 5 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/added-smtp-auth-login.txt'
+  _send_email 'auth/added-smtp-auth-login' '-w 5 0.0.0.0 465'
   assert_success
   assert_output --partial 'Authentication successful'
 }
 
 @test "[user: 'added'] should fail to authenticate with wrong password (login)" {
-  _run_in_container_bash 'nc -w 20 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/added-smtp-auth-login-wrong.txt'
-  assert_success
+  _send_email 'auth/added-smtp-auth-login-wrong' '-w 20 0.0.0.0 465'
   assert_output --partial 'authentication failed'
 }
 
@@ -264,8 +258,7 @@ function setup_file() {
 # Dovecot does not support SMTPUTF8, so while we can send we cannot receive
 # Better disable SMTPUTF8 support entirely if we can't handle it correctly
 @test "not advertising smtputf8" {
-  _run_in_container_bash 'nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/smtp-ehlo.txt'
-  assert_success
+  _send_email 'email-templates/smtp-ehlo'
   refute_output --partial 'SMTPUTF8'
 }
 
diff --git a/test/tests/parallel/set3/mta/smtponly.bats b/test/tests/parallel/set3/mta/smtponly.bats
index a53107fc..66123de6 100644
--- a/test/tests/parallel/set3/mta/smtponly.bats
+++ b/test/tests/parallel/set3/mta/smtponly.bats
@@ -32,7 +32,7 @@ function teardown_file() { _default_teardown ; }
   assert_success
 
   # it looks as if someone tries to send mail to another domain outside of DMS
-  _send_email 'smtp-only'
+  _send_email 'email-templates/smtp-only'
   _wait_for_empty_mail_queue_in_container
 
   # this seemingly succeeds, but looking at the logs, it doesn't
diff --git a/test/tests/serial/mail_pop3.bats b/test/tests/serial/mail_pop3.bats
index c181de79..cb07484a 100644
--- a/test/tests/serial/mail_pop3.bats
+++ b/test/tests/serial/mail_pop3.bats
@@ -24,13 +24,11 @@ function teardown_file() { _default_teardown ; }
 }
 
 @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
+  _send_email 'auth/pop3-auth' '-w 1 0.0.0.0 110'
 }
 
 @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
+  _send_email 'auth/added-pop3-auth' '-w 1 0.0.0.0 110'
 }
 
 @test '/var/log/mail/mail.log is error-free' {
diff --git a/test/tests/serial/mail_with_imap.bats b/test/tests/serial/mail_with_imap.bats
index 14c67b5d..d729c142 100644
--- a/test/tests/serial/mail_with_imap.bats
+++ b/test/tests/serial/mail_with_imap.bats
@@ -21,8 +21,7 @@ function setup_file() {
 function teardown_file() { _default_teardown ; }
 
 @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
+  _send_email 'auth/imap-auth' '-w 1 0.0.0.0 143'
 }
 
 @test '(SASLauthd) SASL RIMAP authentication works' {
@@ -31,14 +30,13 @@ function teardown_file() { _default_teardown ; }
 }
 
 @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
+  _send_email 'auth/smtp-auth-login' '-w 5 0.0.0.0 25'
   assert_output --partial 'Error: authentication not enabled'
-  _run_in_container_bash 'nc -w 5 0.0.0.0 465 < /tmp/docker-mailserver-test/auth/smtp-auth-login.txt'
-  assert_success
+
+  _send_email 'auth/smtp-auth-login' '-w 5 0.0.0.0 465'
   assert_output --partial 'Authentication successful'
-  _run_in_container_bash 'nc -w 5 0.0.0.0 587 < /tmp/docker-mailserver-test/auth/smtp-auth-login.txt'
-  assert_success
+
+  _send_email 'auth/smtp-auth-login' '-w 5 0.0.0.0 587'
   assert_output --partial 'Authentication successful'
 }
 
diff --git a/test/tests/serial/tests.bats b/test/tests/serial/tests.bats
index abcd808a..f28787f8 100644
--- a/test/tests/serial/tests.bats
+++ b/test/tests/serial/tests.bats
@@ -81,13 +81,11 @@ function teardown_file() { _default_teardown ; }
 }
 
 @test "imap: authentication works" {
-  _run_in_container_bash "nc -w 1 0.0.0.0 143 < /tmp/docker-mailserver-test/auth/imap-auth.txt"
-  assert_success
+  _send_email 'auth/imap-auth' '-w 1 0.0.0.0 143'
 }
 
 @test "imap: added user authentication works" {
-  _run_in_container_bash "nc -w 1 0.0.0.0 143 < /tmp/docker-mailserver-test/auth/added-imap-auth.txt"
-  assert_success
+  _send_email 'auth/added-imap-auth' '-w 1 0.0.0.0 143'
 }
 
 #
@@ -416,12 +414,10 @@ EOF
   sleep 10
 
   # send some big emails
-  _run_in_container_bash "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/quota-exceeded.txt"
-  assert_success
-  _run_in_container_bash "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/quota-exceeded.txt"
-  assert_success
-  _run_in_container_bash "nc 0.0.0.0 25 < /tmp/docker-mailserver-test/email-templates/quota-exceeded.txt"
-  assert_success
+  _send_email 'email-templates/quota-exceeded' '0.0.0.0 25'
+  _send_email 'email-templates/quota-exceeded' '0.0.0.0 25'
+  _send_email 'email-templates/quota-exceeded' '0.0.0.0 25'
+
   # check for quota warn message existence
   run _repeat_until_success_or_timeout 20 _exec_in_container_bash 'grep \"Subject: quota warning\" /var/mail/otherdomain.tld/quotauser/new/ -R'
   assert_success