GetResponse
By Intellispire
Mailing & Newsletter bridges
Listbuilding with GetResponse and Joomla! has never been easier.
Simply install the GetResponse Joomla! 1.5, 1.6, 1.7, 2.5, 3.0 and 3.3 Native plugin, give it the list name and your API key (provided by GetResponse), and all new Joomla! signups are then added to your GetResponse list as well.
It's lightning fast and extremely reliable - and of course, since you are doing things the "approved"...