I have a website in WordPress. I paid a company who have excellent programmers and software developers to create a plugin for me. They gave me great support during 3 months after they finished the plugin. Then, I had an issue: suddenly all the emails that were sent from my website said, as usual, that they were successfully sent, but the emails never get delivered to the target emails.
This happened with the general Contact Us form on my website and also with the email functionality of the plugin Probytes created for me. For the Contact Us page which is also a standard Wordpress plugin I was recommeded to use a plugin which is called "Postman" and it fixed it. It helped the emails get delivered. However, the emails that are sent through the plugin that Probytes created for me still do not get delivered (in spite of when the email is sent it says that the message was successfully sent).
I contacted the software developers that created the plugin and they said that within the plugin everything was working as usual (including the smtp configurations within the plugin), so what was preventing the emails from being delivered was the smtp configurations within my server provider (Hostgator). I contacted Hostgator and they said that within the server the smtp configurations are all fine. To make the story short, at the end of the day the developers put the blame on Hostgator and Hostgator put the blame on the developers, and at the end of the day the issue is still there: the emails that are sent from my plugin say that they are successfully sent, but they never get delivered.