Tools|Message Filters lets you do this. Use "contains" to work with just parts of your email address. This can automate the filing or deletion of your unwanted messages. Words like block and reject imply, to me, something better suited to filtering that works on the server before the messages get anywhere near close to being downloaded to your email client. So you could also investigate what your email provider has to offer you for filtering. Go to his website, log into your email there and look for filters or rules.