diff --git a/roles/mail_server/tests/test_optional.py b/roles/mail_server/tests/test_optional.py
new file mode 100644
index 0000000000000000000000000000000000000000..a74b2007b7232263706c974c3a0467f55ccdd5b7
--- /dev/null
+++ b/roles/mail_server/tests/test_optional.py
@@ -0,0 +1,106 @@
+import re
+
+import testinfra.utils.ansible_runner
+
+
+testinfra_hosts = testinfra.utils.ansible_runner.AnsibleRunner(
+    '.molecule/ansible_inventory').get_hosts('parameters-optional')
+
+
+def test_smtp_tls_files(File, Sudo):
+    """
+    Tests if SMTP TLS private key has been deployed correctly.
+    """
+
+    with Sudo():
+
+        tls_file = File('/etc/ssl/private/parameters-optional_smtp.key')
+        assert tls_file.is_file
+        assert tls_file.user == 'root'
+        assert tls_file.group == 'root'
+        assert tls_file.mode == 0o640
+        assert tls_file.content == open("tests/data/x509/parameters-optional_smtp.key.pem", "r").read().rstrip()
+
+        tls_file = File('/etc/ssl/certs/parameters-optional_smtp.pem')
+        assert tls_file.is_file
+        assert tls_file.user == 'root'
+        assert tls_file.group == 'root'
+        assert tls_file.mode == 0o644
+        assert tls_file.content == open("tests/data/x509/parameters-optional_smtp.cert.pem", "r").read().rstrip()
+
+        tls_file = File('/etc/ssl/private/parameters-optional_imap.key')
+        assert tls_file.is_file
+        assert tls_file.user == 'root'
+        assert tls_file.group == 'root'
+        assert tls_file.mode == 0o640
+        assert tls_file.content == open("tests/data/x509/parameters-optional_imap.key.pem", "r").read().rstrip()
+
+        tls_file = File('/etc/ssl/certs/parameters-optional_imap.pem')
+        assert tls_file.is_file
+        assert tls_file.user == 'root'
+        assert tls_file.group == 'root'
+        assert tls_file.mode == 0o644
+        assert tls_file.content == open("tests/data/x509/parameters-optional_imap.cert.pem", "r").read().rstrip()
+
+
+def test_certificate_validity_check_configuration(File):
+    """
+    Tests if certificate validity check configuration file has been deployed
+    correctly.
+    """
+
+    config = File('/etc/check_certificate/parameters-optional_smtp.conf')
+    assert config.is_file
+    assert config.user == 'root'
+    assert config.group == 'root'
+    assert config.mode == 0o644
+    assert config.content == "/etc/ssl/certs/parameters-optional_smtp.pem"
+
+    config = File('/etc/check_certificate/parameters-optional_imap.conf')
+    assert config.is_file
+    assert config.user == 'root'
+    assert config.group == 'root'
+    assert config.mode == 0o644
+    assert config.content == "/etc/ssl/certs/parameters-optional_imap.pem"
+
+
+def test_mailname_file_content(File):
+    """
+    Tests the system mail name file content.
+    """
+
+    mailname = File('/etc/mailname')
+
+    assert mailname.content == "parameters-optional"
+
+
+def test_postfix_main_cf_file_content(File):
+    """
+    Tests if the Postfix main configuration file content is correct.
+    """
+
+    config = File('/etc/postfix/main.cf')
+    config_lines = config.content.split("\n")
+
+    assert "myhostname = parameters-optional" in config_lines
+    assert "mydestination = parameters-optional, parameters-optional, localhost.localdomain, localhost" in config_lines
+    assert "mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 10.31.127.20" in config_lines
+    assert "smtpd_tls_cert_file = /etc/ssl/certs/parameters-optional_smtp.pem" in config_lines
+    assert "smtpd_tls_key_file = /etc/ssl/private/parameters-optional_smtp.key" in config_lines
+    assert "  reject_rbl bl.spamcop.net" in config_lines
+    assert "  reject_rbl zen.spamhaus.org" in config_lines
+
+
+def test_local_aliases(Command, File, Sudo):
+    """
+    Tests if local aliases are configured correctly.
+    """
+
+    send = Command('swaks --suppress-data --to root@localhost')
+    assert send.rc == 0
+    message_id = re.search('Ok: queued as (.*)', send.stdout).group(1)
+
+    with Sudo():
+        mail_log = File('/var/log/mail.log')
+        pattern = "dovecot: lda\(john.doe@domain1\): msgid=<[^.]*.%s@[^>]*>: saved mail to INBOX" % message_id
+        assert re.search(pattern, mail_log.content) is not None