Today, I wrote a simple MyBB plugin, Registration eMail Check (RMC). The plugin first verifies whether the email has a valid format, then compares the email host with a number of hosts which were explicitly disabled by the administrator (the plugin comes with a decent list of well-known one-time address providers), and finally tries to communicate with the corresponding mail server in order to verify whether the address actually exists.
I wrote the plugin for two reasons: First, because I wanted to prevent automated bot registration with non-existing email addresses. When I look through lists of users waiting for activation I find an ever growing amount of accounts which were obviously generated automatically, using non-existing email addresses. Second, because I don’t want people to use anonymous one-time email addresses when registering in forums where a certain mutual trust is mandatory.