Some Email servers (hubs) are blocked

When I was performing experiments in setting up custom emails I found that there was a pattern to why certain emails were not being delivered.

In many cases I found that the only way of determining how and where an email was blocked was to setup a dummy emailer and try many combinations of addresses.

As I use Gmail I used the "Show Original" menu option to look at the complete data dump that the recieved email consists. Doing this you can determine where the message has been routed and what checks have been made on the message.

I created a series of php mailer scripts and I was surprised to see that when run on different webservers the results were different. In particular, TSOHost hosted email was quite often blocked by Microsoft British Telecom (BT) derived email clients.

Background

This page will be placed on both my servers and have tests sending emails to suspected addresses that have seen to have been Blacklisted in the past.

The 4 php files also need to be uploaded to both servers. These files need to be removed from the server when I am not making tests as they will potentially send emails when a robot or spider probes the website.

The Tests:

• Test 1 - blacklist1.php email to a Hotmail Outlook address
• Test 2 - blacklist2.php - email to a btInternet address
• Test 2a - blacklist2a.php - email to a btInternet address with a redirect on the Parish Council server.
• Test 3 - - blacklist3.phpemail to a Gmail address (without a redirection at one of my servers)

The first test seems to be the problematic one. On hostinguk the email gets sent and delivered but initially is goes to the "Junk" folder.

The second test shows that I can get the blacklisting by btinternet to work by routing through a redirect on a HostingUK server.