There is a limit of 250 email messages/hour from your script. Emails originating from regular e-mail clients (Mail.app, Thunderbird, Outlook, Eudora, and webmail) are not counted. Only emails sent from mailing list scripts or other mailing scripts are.

We put a limit of 250 email messages/hour to prevent load spikes and spam. If you have very large mailing lists, it is recommend that you get your own e-mail server, which MX record can be modified from CPanel.