For me, email is the 'master key' for most of my online accounts (because password resets are done via email so if your email account is compromised an attacker can quickly leverage access to other services) and email security is top priority. I didn't see anything about using two-factor authentication with this service - is it available?
Also, your site only supports obsolete HTTPS protocols. TLS 1.0 and SSLv3. You should drop SSL 3 and enable support for TLS 1.2. Here's a test you can run with feedback and resources to learn more about secure configurations: https://www.ssllabs.com/ssltest/analyze.html?d=migadu.com&s=...