Using a valid From address
Validating an email address is a really hard task. Some tried huge regular expressions to solve this, but they are unreadable and do not cover every case. This leads to the conclusion that, as a sender, you should not only use a valid address in your
From header, but also one that is simple and practical, because some exotic, but still valid, addresses might not be processed correctly by MTAs and other involved systems like spam filters.