Although we don't provide any kind of support to any 3rd. party software, we provide - for few dollars - installation and configuration of a light copy of Interspire email marketer.
(Read more about this script at: www.interspire.com/emailmarketer/).
So if you find it good and sufficient for your needs you can still use it but without any kind of support from our side, you have to contact the developer company to order your licensed copy along-with support package.
This is not the only software you might use in order to send emails, you can use any mail client program like MS Outlook, but if you want to send to huge mail list, so you need a specialized software to manage your mail list like Interspire email marketer.
Caution: Interspire email marketer has it's built in mechanism to limit the sending intensity, so you will not reach the max limit of sending appears at servers plans and features page.
We recommend Mail list King (Business Edition 199.5USD, Personal Edition 99.5USD), but you are not forced to use it, try any FREE software, just Google for "Free Email marketing software OR Free mail list management tool".