When WordPress needs to send an email for some reason (such as a new user registration), it sends it from wordpress@sitename.com, where sitename.com is the domain of your site.

However, more than often this generated address doesn’t actually exist (unless you  explicitly create it), and this can confuse your site’s users. Personal Email is a plugin that changes this default address into the one you set as your site’s admin email under the Settings > General admin menu.

Links

• WordPress.org page – read more and download stable version
• GitHub repository – download development version and contribute to the code