Application Package Peoplecode:
PT_WF_NOTIFICATION.Notification.OnExecute
method Send
/* SendMail(0, &strEmailCC, "", &strEmailBCC, &Subject, &Message, &strFileNames, &strFileTitles, &tempEmailReplyTo, ";", &ContentType);*/
SendMail(0, &strEmailTo, &strEmailCC, &strEmailBCC, &Subject, &Message, "/path/path/filename.ext", "xxx.txt", "From_Notify@rver.xx.yy.zz", ";", &ContentType, &tempEmailReplyTo, "sender@srvr1.xx.yy.zz");
Further reading:
SMTP
Internet Messaging protocols (SMTP,POP3 and IMAP4)
SPAM Filtering