In Developer Edition organizations and organizations evaluating Salesforce during a trial period, your organization can send mass email to no more than 10 external email addresses per day. This lower limit does not apply if your organization was created before the Winter '12 release and already had mass email enabled with a higher limit. Additionally, your organization can send single emails to a maximum of 15 email addresses per day.
Developer editio is limited to 10 external email. However if you can manage you can send more emails to internal users. Except it you should contact salesforce support for help regarding it. But I am not sure you can log support with free edition, you must be a partner.
In Developer Edition organizations and organizations evaluating Salesforce during a trial period, your organization can send mass email to no more than 10 external email addresses per day. This lower limit does not apply if your organization was created before the Winter '12 release and already had mass email enabled with a higher limit. Additionally, your organization can send single emails to a maximum of 15 email addresses per day.
check out this link http://help.salesforce.com/HTViewHelpDoc?id=limits_email_mass.htm&language=en_US
Thanks
Developer editio is limited to 10 external email. However if you can manage you can send more emails to internal users. Except it you should contact salesforce support for help regarding it. But I am not sure you can log support with free edition, you must be a partner.