https://my.wealthyaffiliate.com/training/analyzing-data/opt-ins

This might help you decide.

There are several plugins to create opt-in forms, but the form will have to be linked to an autoresponder if you want to send your subscribers email messages.

Tria mentioned Aweber, and that gives you both opt-in forms and the autoresponder combined. There are many other autoresponders around that do this. Get Response is another service.

There are free autoresponders services around, but I do not recommend those because the companies will include ads for other things into your messages - not something you would want - or you will find other conditions that limit what you can do.

For WordPress self hosted sites (not WP dot com sites), Gravity Forms is an opt-in form builder. Having an opt-in form without an autoresponder is pointless, unless all you want to do is gather email addresses.

~Jude

AWeber.