You have to use a paid service like aweber. You can get a cheap software to install on your own server but your delivery rate would suck.

An optin form without the backend = the autoresponder behind it, it completely useless. Wordpress or not... it doesn't make any difference.

You either have to (read: must) use a commercial service like getresponse, aweber etc. or (if technically advanced) use your own script AND a delivery server.

Advisable use the reputable(paid) one. No free lunch in this world. Paid one usually have the better service especially when you have problem with your Auto Responder. I have very good experience with them. If you are seriously in Internet Marketing, get the paid one. Aweber are one of the good one. They are other equally good Auto Responder company. You have to find it yourself who suit your need. Do remember if you have choose Auto Responder "A" and have a lot of list subscriber, it is very difficult to move your list from Auto Responder "A" to Auto Responder "B" company.

Yes, there's no free lunch in this world...

I have heard that Aweber not only has email opt-in forms for you but also a lightbox you can use, does GetResponse have this as well?

Email Marketing Software - YMLP

They have Free Trial with no credit card / paypal needed up front.

After that their is a free service with for the first 1000 emails a month (just without analytics and single opt in). Great for if your building up a list and want to see some return first.

Not had any issues with spam filters and my emails go right through.

I am really like them so far.

If you are serious about your business, you will not go with a free autoresponder...your list will become the lifeblood of your business, you want to invest in protecting, growing and nurturing your list. Go with Aweber, 1Shoppingcart, GetResponse, etc...the monthly fee you will incur should be something you easily recoup in your first month or two of operating your online business.

Jeff

I agree with all of the comments above. I mainly use aweber and it is fantastic. Getresponse is great too .. BUT .. if you really want a free option you can use this plugin, GWA Autoresponder to get started.

Good luck )