Your mailing application can't function without proper mail settings configured. There are three options for sending mail:
The "Default sending method" will use the default MTA, or "Mail Transport Agent," such as sendmail, qmail, etc.
You can also force the application to use sendmail only.
For sending mail using an SMTP server, you'll need to specify additional information, such as server, username, password, etc:
You can add mail settings by going to the Settings > Mail Settings menu option.
When adding mail connections, you'll notice additional configuration options:
Each of these options allows you to further control your mail configuration.
Emails/SMS Per Cycle: Specify a number here if you have more than one mail settings connection. You can have the application send a certain number of email or SMS messages from one connection, then move on to the next connection.
Enable sending throttling and pausing: Check this option if you wish to reduce your mail servers' load by forcing a pause after a specific number of emails or SMS message are sent.
Limit number of emails/SMS to send for a specific time period: Check this option if you'd like to limit the number of email or SMS messages sent in a given time period (hour or day):
Used by User Groups: This powerful control lets you specify which mail sending options are used for each user group. If you set up your mailing application for different clients, for example, you may want separate SMTP settings for each client (group). See, also, the article on User Groups.