Protect open registration / reCaptcha

Hi Folks,

we’re absolutely new to Mattermost but installation and setup went really smooth. We actually have the need to enable open registration for this server as we want to grant access to a broad group of users.

Now we wonder how mattermost protects such an open installation from having bots flodding the system? We could not find any hint on implementing reCAPTCHA or something similar.

Is just the opt in mail meant to protect the system? How long will mattermost keep registrations, that don’t confirm by mail?

Hope you can help as we’re a bit afraid opening the server without some protection…