There is no messages either in the queue or in the sent message folder area for any user.

I have tested on the development site and I can add a message to the queue and send an email by clicking the links manually as a test.

On our live site this isn't the case. I click on the following links and get a blank page:
- Url of cron task to process mailers rules
- Url of cron task to both process mailer rules into queue and then to process mailqueue

The page opens but it seems like it doesn't do any processing

I click on the Url of cron task to process mailqueue link and it says No messages in messages queue to be sent. So it seems I can access the files.

Hello

Sorry I have PM'd you the details.

I wanted to also add I was working from another place (so I had a different IP) and the manual commands (when clicked) were working and also triggered the cron job to work. However I went to change the mailer settings to what I wanted and then the cron stopped again and the 1st and 3rd automation links stopped working also. I have tried this morning from our main office and queuing the emails and the link to run the queue + send aren't working still, but the second command (to send the emails) work successfully and sent 76 emails that were in the queue (that were added when it worked from when I was on a different network as explained above)
I also have an open ticket with our sever techs to see if they can see any issues. They said they have added the sites IP address into the servers HOSTS file to see if this will remedy the issue as we are running through a CDN (Stackpath) and we believe that this could be causing the issue but that didn't seem to work.