diff --git a/test/helper/sending.bash b/test/helper/sending.bash
index ed29a98a..12a3d260 100644
--- a/test/helper/sending.bash
+++ b/test/helper/sending.bash
@@ -48,7 +48,12 @@ function _send_email_unchecked() {
       ( '--port' )   PORT=${2:?--port given but no argument}     ; shift 2 ;;
       ( '--data' )
         ADDITIONAL_SWAKS_OPTIONS+=('--data')
-        ADDITIONAL_SWAKS_OPTIONS+=("@/tmp/docker-mailserver-test/emails/${2:?--data given but no argument provided}")
+        local FILE_PATH="/tmp/docker-mailserver-test/emails/${2:?--data given but no argument provided}"
+        if _exec_in_container_bash "[[ -e ${FILE_PATH} ]]"; then
+          ADDITIONAL_SWAKS_OPTIONS+=("@${FILE_PATH}")
+        else
+          ADDITIONAL_SWAKS_OPTIONS+=("'${2}'")
+        fi
         shift 2
         ;;
       ( * ) ADDITIONAL_SWAKS_OPTIONS+=("'${1}'") ; shift 1 ;;
diff --git a/test/tests/parallel/set3/container_configuration/hostname.bats b/test/tests/parallel/set3/container_configuration/hostname.bats
index a525ecb2..c0a23b19 100644
--- a/test/tests/parallel/set3/container_configuration/hostname.bats
+++ b/test/tests/parallel/set3/container_configuration/hostname.bats
@@ -207,7 +207,7 @@ function _should_have_correct_mail_headers() {
   # (eg: OVERRIDE_HOSTNAME or `--hostname mail --domainname example.test`)
   local EXPECTED_HOSTNAME=${3:-${EXPECTED_FQDN}}
 
-  _send_email --from 'user@external.tld'
+  _send_email --from 'user@external.tld' --data "Date: %DATE%\nTo: %TO_ADDRESS%\nFrom: %FROM_ADDRESS%\nSubject: test %DATE%\n%NEW_HEADERS%\n%BODY%\n"
   _wait_for_empty_mail_queue_in_container
   _count_files_in_directory_in_container '/var/mail/localhost.localdomain/user1/new/' '1'