Hello.
You can try to send e-mail via API in "msgEdit_OnAfterMessageSaved" event in ~\CMSModules\MessageBoards\Controls\MessageBoard.ascx.cs file.
E-mail message can be sent via following example code:
CMS.EmailEngine.EmailMessage msg = new CMS.EmailEngine.EmailMessage();
msg.From = "mymail@domain.com"; // use valid e-mail
msg.Recipients = "mymail@domain.com"; // use valid e-mail
msg.Subject = "Custom BizFrom e-mail";
msg.Body = "The value of the FirstName field: "
+ CMS.GlobalHelper.ValidationHelper.GetString(
this.viewBiz.BasicForm.DataRow["FirstName"], "N/A");
CMS.EmailEngine.EmailSender.SendEmail(msg);
Best Regards,
Radek Macalik