You need to use a proper autoresponder. Free autoresponders offered by hosting services are not up to the job simply because the hosting service cannot allocated enough resources from their business to manage the never ending task of spam management.
So even if it’s free, if it can’t deliver your marketing message it might as well not exist.
www.Aweber.com and www.GetResponse.com are two professional autoresponders. Everyone develops their own preferences. You might also take a look at www.MailChimp.com which is free for up to 500 subscibers but then escalates quite steeply in price.
However, MailChimp looks like an industrial grade service with some big industry users so may well be worth considering if you are expecting perhaps to develop a small membership site where you will not run into escalating charges if your list stays small.
More recently, MailChimp has removed the autoresponder function from the free list so although you can broadcast you can no longer automate the process.
www.AutoresponsePlus.com takes a one off purchase payment but is free thereafter. I notice that they are teamed up with Mark Joyner which is a substantial recommendation.
Total Business Cart. This is a complete shopping cart with autoresponder services, split testing facility, affiliate management as well as the shopping cart. Developed to meet the needs of the internet marketer and used by many of the big names. I use Total Business Cart (not that that puts me among the big names!) and heartily recommend it..
TotalBusinessCart is actually a private label version of 1shoppingcart (as are many of the other shopping carts available). The owners, Paul and Philly, are internet entrepreneurs like us and this was their route to the market. They provide the 1shoppingcart product but with anglicized service. Support them – they’re in the same business as you are!
You may have difficulty with the Verified Opt-in process which is intended to protect against spam. 1SC reports a very high success rate of email delivery for the Tier 1 autoresponder service provided to their customers using Verified Opt-in. Unfortunately, the setup process is rather obscure and I found that I needed to draw it out as a reminder for use each time I set up a new product.
You will find my Verified Opt-in Process diagram here.