To protect your mailbox from undesirable correspondence, do not publish your e-mail address on Internet forums and switch on the server-side spam filter provided by the SpamAssassin software.
When you need to publish your e-mail address, create a disposable e-mail address - e-mail alias - for your primary e-mail address, and publish it instead. All messages sent to the e-mail alias will come into your mailbox. Once you start getting spam, remove that alias and create another one. If you have a mailbox at another domain or mail server, you may want to set up a disposable e-mail forwarder.