I would suggest Send Steed through LeadsLeap a Traffic Generation Site. SendSteed is free through LeadsLeap, you have to be a member but it's free to join and stays free. With the free version of LeadsLeap you can have 10 lists and unlimited subscribers, there is also a Page Builder, a Popup creator, called PopUpXpert, plus you can Track and Tag your Subscribers.
The paid version is $19.90 a month if you sign up within the first 24 hours. After that it's $27.00 a month and you can have unlimited list and unlimited subscribers. Most services will charge you extra as your list grows. Plus you can advertise at LeadsLeap, and there are 5 Ways to get paid.
There is also an affiliate program, so if you signed up and got two subscribers, your membership is paid for.
The Tracker tracks real visitors and eliminates bot Traffic. It also tracks the duration of your visitors. I can't say enough about LeadsLeap. Here are links to the Tracker and the SendSteed Autoresponder. The Professionalism and State of the Art Traffic Generation at LeadsLeap speaks for itself.
If you have questions, let me know.
Not interested in trying to sell you anything, just give advise. Any quality autoresponder works fine. The big thing is how do you use the. If you generate shotty leads and broadcast to them over and over you wont get delivery. See Autoresponder have to manage their delivery score to maintain service to all business. So when they see spammy mailing they simply down grade you to there shot delivery IP's that result in poor delivery.
I get great results with Getresponse using it only to deliver scheduled emails and never broadcast. I own a an Autoresponder business and we focus on quality...there are not IMer and Solo Ad suppliers in my business because the cost of IP's is top much.
So use responsibly and your fine with any. NOW if you want tp sell solo ads...you better get good at managing your own hosted servers, IP's etc.