Thank you for your feedback. We are sorry to hear that you could not get it working.
You could have, and still can, contact our support via contact form or email. That is what our "Contact a developer" webpage is all about - direct contact to the persons that know how the software works.
I am confident that we can solve your problem to your satisfaction, the other reviews certainly support this claim.
As of the uninstallation: we decided to not drop the database tables during uninstallation to avoid having users that unintentionally deleted their data during an upgrade. This is also expressed in the message that you misinterpreted as an error message.
I dont know how you can compare it to Joomla's Email ! this Is a completely different solution. Also there are hundreds of users who are successfully using this. I would suggest you read the documentation or use our Forum for Community for support.. If you need professional Support get a Support subscription..
It is not one that you can pick up and utilise in hours or days, in my view it needs a long learning curve, but it is definitely worth it at the end. Support is great too and the developers are very helpful and go out of their way to solve any issues
Apparently this reviewer did not have their cron working. There are actually 3 ways to retrieve mail. This method which requires a button click and 2 automatic methods: an internal cron and an external cronjob.
Our forum discusses this setup and also the help section within powermail.