Free email marketing software is not easily to be found. A rich full featured software solution is probably worth many more times its market value as a good solution will really help your business. Taking this into consideration you might want to check out paid solutions instead of free (open source) software tools. Email marketing tools are on the market for just a few hundred dollars already. Depending on your needs you might want to check out the more rich solutions, and thus more expensive solutions.

Back to what you came for, free marketing mailing list software. You may want to check out the following free solutions:

PHPList PHPlist is a double opt-in newsletter manager. It is written in PHP and uses an SQL database for storing the information. PHPlist is software that runs on a server. Visit PHPList