I'm currently using a server-side SQL based mailing list program called Php-List on multiple sites and it works fairly well. But installation and setup is quite cumbersome, quirky and the interface is not well organized... neither is the code... with pieces all over the place in random fashion.
Customizing the "look & feel" and full site integration are both tedious and painful. Upgrading the version is made more complex since multiple edits need to be manually transferred each time. Also, probably due to a poor English translation, descriptions and instructions within certain areas of the user interface are contradictory and unclear. You just have to play with it and remember what you did last time it worked.
It's supposed to be so my customers can send out their own newsletters... after supplying a written tutorial, about half of them seem to stumble through it okay and the other half just hire me to do it for them. So not quite easy enough for most average people to use. I'm looking for something that's as easy for them as using a blog or discussion forum.
It also must be easier to set up and integrate into a site than Php-List. I have no problem getting dirty and writing CSS or HTML by hand. Nor do I have any problem editing the program code. Perhaps what I'm looking for is a solution that is more organized, a better GUI, and template or "skin" based. Therefore, if I spend many hours customizing a skin, I can simply update the program and re-use my custom skin without having to reproduce the tedious setup over and over. (I currently maintain a list of about 25 things I must manually edit or add to multiple files in multiple directories each time I install or upgrade Php-List)
A great example of what I'm looking for is very much like WordPress or phpBB. They're both easy to install and customize yet powerful and packed full of features. They're also VERY well organized making customization less painful.
So enough yammering for now... anyone know of something, besides Php-List, with many of the same features as Php-List; maintaining a mailing list with a server-side database, custom sign-up pages, automatic opt-in opt-out, allowing custom HTML newsletter templates, etc?