Need A to Z troubleshooting guide for smtp

Hi,

Im seeking an A to Z troubleshooting guide to SMTP mail. The issue is that for some reason my whmcs created email is not going out.

I am sending auto mail, but not created mail. There are number of reasons:

1. Having mail issues.
2. This is a new VPS .
3. I have a new host name.
4. Due to recent past that things that i need seem to elude me until something breaks weeks later.
5. I want to know its working not hope its working and why.
6. I think my port is right but im not sure.
7. I think i have all server features i need but im not sure.
8. I think i have the right setup but im not sure.
9. The email that i use for my smpt, i went to that email setup in cpanel and used the email helper to help me setup my smtp, but im still not sure its right.


So i need something that will take me from basic square one on how to setup smtp mail with whmcs or not, either way. But i want to check everything from A to Z so that when and if i need to do a ticket on this i have all the things checked to be sure i have it right. And also by the time im done this will work everyday every time .

Any reliable docs out there like that?

Thanks

 

I actually googled SMTP for dummies, hee hee... But this here does not look too bad computer.howstuffworks.com/e-mail-messaging/email3.htm

 

This is not too bad either exim.org/exim-html-current/doc/html/spec_html/ch-access_control_lists.html