Is it possible to somehow send an email from Openserver or Denwer using mail ()?
You need to put the mail server (for example, sendmail (in Denwer is a stub)), then in the file php.ini set corresponding. settings [mail]
Have you looked into the OpenServer settings? There, the "Mail" tab, select or store in a local folder, or send via a remote SMTP server. And it is not necessary to put Mail servser. Anyway, the manual in Russian, where everything is described in detail. In addition, there is a forum . And about Denver it's time to forget. Already more than a year watching:
Регистрация требуется в связи с будущим выходом Денвера-4.
The project stalled, and OpenServer is regularly updated (the last time - August 19, 2012), not so buggy, the settings and features are in good order above.