diff --git a/test/tests/serial/permit_docker.bats b/test/tests/serial/permit_docker.bats
index 2ebf5e3e..617e4a46 100644
--- a/test/tests/serial/permit_docker.bats
+++ b/test/tests/serial/permit_docker.bats
@@ -68,7 +68,7 @@ teardown_file() {
   _reload_postfix mail_smtponly_second_network
 
   # we should be able to send from the other container on the second network!
-  run docker exec mail_smtponly_second_network_sender /bin/sh -c "nc mail_smtponly_second_network 25 < /tmp/docker-mailserver-test/emails/nc_raw/smtp-only.txt"
+  run docker exec mail_smtponly_second_network_sender /bin/sh -c "while read -r LINE; do sleep 0.5s; echo \"\${LINE}\"; done < /tmp/docker-mailserver-test/emails/nc_raw/smtp-only.txt | nc mail_smtponly_second_network 25"
   assert_output --partial "250 2.0.0 Ok: queued as "
   repeat_in_container_until_success_or_timeout 60 mail_smtponly_second_network /bin/sh -c 'grep -cE "to=<user2\@external.tld>.*status\=sent" /var/log/mail/mail.log'
 }