Another good one I use is QIOS Pelican, a program made specially to deal with newsletters.
The best thing about it is: it is free.
One slight drawback for some people might be that you have to set up your subscription to your mailing list yourself, for example through a form on your website, but once that is done and you have some subscribers in your database, you are good to go.
As for databases,
QIOS Pelican can handle a wide selection of those.
They are:
- Microsoft Access Database
- Microsoft Excel Sheet
- Microsoft Exchange Server via WebDAV
- Microsoft Outlook Mailbox
- Microsoft SQL Server
- Microsoft .NET DataSet over HTTP
- Oracle Database
- MySQL Database
- Text File
- Custom OLE DB Connection
- Custom ODBC Connection
The program also contains an editor for your email, allowing both text and HTML.
If you newsletter uses a similar layout for every one you send out, all you have to do is open the editor and change the things that are new in the newsletter.
After that, you just let the program look at your mailing list which is in your database and let it send out your newsletter to all subscribers in the list (although it is also possible to untick names to exclude them from the mailing list).
More information about the program can be found
here.
Although it is a free program, the staff at QIOS always answer your queries and requests for support, and they run a forum too.
Go and have a look, I have used the program for a number of years now and I am quite happy with it.