Forum Moderators: buckworks
and not be filtered as SPAM
Welcome aboard beeman, but this part has nothing to do with the mailer itself - mostly. The mailer script must put out appropriate headers which, if not present, will contribute to the overall "spam score" of an email in most algos, but generally the mail goes to the spam box based on parameters detected from the originating server and the overall content of the email (A simplified explanation.)
To check your content, there are many tools on the web that you can paste your message into to check for spam score. I've tested these and even so, many of them still wind up in spam from a valid non-blocked server. It's a hard nut to crack.