Drupal sends emails to Hotmail but not to other accounts I have a problem when Drupal sends email messages. I use the Rules module for doing it.

When the email is sent to a Hotmail account, the email is sent successfully; with other accounts (e.g. Yahoo, Gmail), the email is not received. The "recent log entries" shows the email as successfully sent, but the account doesn't receive it.
Likely the problem is not in drupal, but in server environment. You could use Drupal SMTP Support module to bypass this.