Sending email without getting blocked

I have a PHP application that needs to send outgoing mail. It keeps getting blocked by Comcast because it doesn't have a PTR record.

The web app uses a 3rd party DNS. It uses CentOS and is running named, but the ns1 and ns2 addresses are to a 3rd part server.

Can someone explain how I can setup my server so it doesn't get blocked? I think I need a PTR record and an SPF record. We were using Google business apps to send email, but they are horrible - there is a limit on the amount of email you can send out and it's about a 1/3 of what our web app uses.

It just crazy how hard all this anti-spam stuff has made it to send out emails. Gmail is the only company I've seen with decent spam detection =/

Here's how you can increase mail deliverability:

1. Your server needs to have a valid hostname like: server.somedomain.com
2. The reverse DNS record of the main server IP needs to match the hostname
3. You need to configure the mail server with the domain you want to send mail as and email account.
4. you need to change your php application to send using smtp authentication agains the configured email@domain.com
5. you need to set up a SPF record for the domain
6. you need to set up domain keys for the domain

Happy spamming :)