Recently I discovered very good way how to create reliable SMTP relay solution and outbound SPAM protect for any cPanel server which I want to share with you. Many known Hosting providers sell you service with already blacklisted ip address. That can be very frustrating, but fortunately we have fix for that. Basically here is the thing you need to do.
1) As you and I know every cPanel come with Spam Assassin. By default it's disabled and that is okay, but hey why don't we enable Spam Assassin to filter outgoing emails as much as it is awesome for incoming email. How to do that? Once you are in the WHM you can go to the search bar in the top left and type Exim and then choose the Exim Configuration Manager option. Once you are on the Exim Configuration Manager page you will stay on the Basic Editor, then you will select the SpamAssassin Options. If you do not see it then there will be a little blue arrow pointing to the right to let you scroll to see the other options. The last one being SpamAssassin Options.
More details you can read here:
http://carvertown.com/enable-outgoing-spam-filtering-using-spamassassin/
2) Okay now that this is enabled sign up here https://sendgrid.com/ . What is Sendgrid? SendGrid is a Boulder, Colorado-based transactional email delivery and management service. The company was founded by Isaac Saldana, Jose Lopez, and Tim Jenkins in 2009, and incubated through the TechStars accelerator program. So yes we can say its very similar business as Mail channels do, BUT big difference here is that they give 12,000 emails FREE OF CHARGE for first 45 days (enough to sort all things on server and stabilize things). Prices are very competitive after with only $9 for 40,000 emails / monthly.
Check price list here:
https://sendgrid.com/pricing
3) Now that you got access to Sendgrid Dashboard please go to https://app.sendgrid.com/settings/mail_settings , scroll down to the bottom of page and enable Spam Checker (this will be secondary checker so yes filtered here even :)
4) When this is finished we need to integrate Sendgrid with cPanel server. Detailed instructions how to integrate can be found here:
https://sendgrid.com/docs/Integrate/Mail_Servers/exim.html
(Section cPanel)
One note:
Restart all email exchange services and not just exim. That's pretty much all. Now you can follow up in real time how outgoing emails are going from app.sendgrid dashboard using awesome functions there like overview, suppression and etc.. Even you can get there review about bounces and spam messages so you can track source on server and easily disable.
I hope this article can be useful to anyone who experience email delivery or spam issues.