Hmm. I'm having a problem with this plugin too.
Marcus has a line at the bottom of his product page saying "support is not guaranteed. Purchase at your own risk"
You're right, there IS no support forum.
Pity really, because when I clicked the ‘delete unsubscribers from database’ button in the plugin’s ‘Option’s page, it crashed the sending process permanently.
The 'create newsletter' part still works, but I can't use the subscribe widget or send the newsletter so it's basically useless at present.
It just seems silly to develop something that - if it worked - would easily be worth $30 and then not support it. Consequence? Well, he's got my $30 but if I can't get it working, then I won't be recommending it onwards.
Should it matter to Marcus? Yes - do a quick search or "WP newsletter plugin" now and see where my blog posts fall (www.mukaumedia.co.uk). Currently, they're positive and comlimentary.