To use a CGI/PHP script for sending emails.

Don't quote me, I am not an emailing expert... but had seen a lot of stuff.

First of all, if and when they blacklist you (your server) it's not about your "intentions". It is about the perceived 'reality' = that you are sending out mass mailing. It is not that YOU get blacklisted. It is your server or your ISP.
Not to mention that your own host will limit (or ban) your ability to send too much mail. Usually, it is in their TOS.

Live example: In Canada Shaw is one of the biggest telecom companies and there was a time they were on blacklist at many major email providers because a lot of Shaw customers were sending spam en masse... left and right.
My wife used to have a user@shaw.ca email address and sent me an email from upstairs... and my email provider automatically put it in the junk. (Nowadays they are better!)

I don't really understand the bit about paypal: it does send email to the vendor and to the buyer - no need for your script.
Furthermore, there is a feature in aweber where you can set up that every buyer of yours gets automatically on your "buyer list" (just set it up).

Decent membership scripts have modules/plugins/whatever for integration with major AR.

(Don't know anything about forums...)

Yes, I have read in this forum quite a few posts by members/warriors who run their own "in-house" mailing lists. Maybe they know something that we don't...

As the warrior above stated, you will hardly need to use a script. However, if you decide to do it I don't think there is a way to prevent your email from going to the spam folder. Maybe you can try to avoid HTML and send only text messages, but there is no guarantee that it will actually help.

I use 2 autoresponders, Aweber and Interspire (self-hosted). Based on my experience, I can say that Aweber is much, much better when it comes to this problem.

Here is a test I made last week...

I have a membership site about IM and I send a PLR product to my members every week. I always use the subject "This Week's PLR Product", so they already know what they will find inside the email even before opening it.

I always send the message using Aweber, and my average open rate is 45% - 50%. However, last week I decided to make a test and send the email using Interspire. I exported my list from Aweber and uploaded it to Interspire and sent the email. My open rate was 23% .

I think that after this test there is no doubt that Aweber rocks when compared with self-hosted autoresponders. If I were promoting a product I would have sold 50% less with Interspire than with Aweber!


William

Thanks both of you guys for your replies.
About Paypal...I heard that Paypal send a customer a notification, but we can't include the download address for the product. So I have to use another script for that (unless you use clickbank or something like that).