Do you have TLS hosts I can test (Normal, Deprecated Version, Mandatory, None)? is a normal TLS host. Per the RFCs, it will offer and optionally do TLS with any email sent to it. If the sender accepts the TLS offer and negotiates a TLS connection, the email will be sent encrypted, otherwise it will be sent in plain text. All emails are discarded. does not offer and will not do TLS, so any emails sent to it will be in plain text. All emails are discarded. only offers TLSv1. Use it to test an email system configured to not allow such an old and less secure version. does not exist in DNS. Use it to test what an email system does with an invalid domain name.

Mandatory TLS offers and forces TLS. It requires either a subscription or a single-use token (available on the test page).