Hello !
I am a professional email marketer and web developer. I have developed a great mass mailing software which can work great for your needs. It's fast and it's simple. It also have SMTP Rotation script inside so you can add multiple email accounts to "load balance" large campaigns on more SMTP's.
Also it can design emails in HTML, load email lists in .csv/.txt./all excel files and also it has a feature to check if email address is good or not, if email address is bad he won't send it, that way you can avoid bounces !
It has more great features, if you are interested contact me on PM so you could try it out before purchasing, if you won't like it i have one more great solution for you !
Please get in touch with me !
Best Regards!