This is a basic mailing list signup form that you can put on your site. It contains the following features:

• Signup form block you can place anywhere on your site, with customizable labels and messages.
• Signup form validates that an email address was provided, that it is a valid format (contains an '@' and '.'), and that the person isn't already signed up. 
• A confirmation email will be sent to new subscribers with a link they must click to complete the subscription.
• An email will be sent to the site administrator when someone signs up and again when they confirm their subscription.
• A dashboard report lists all of your email list signups. The list can also be downloaded as a .csv file.
• Highly configurable styles for the signup form and error/success messages (see below for more details).
• Error/success messages can either be displayed in the block itself, or elsewhere on the page (see below for more details).
• Email templates can be easily changed (see below for more details).

Note that this package provides basic functionality only. Specifically, it does NOT do the following:

• It does NOT manage your email list for you. It only provides a way for people to sign up -- it does not allow them to unsubscribe or change their address.
• It does NOT send emails to your list. It only sends emails to individuals when they first sign up. When you want to actually send an email to your list you need to paste the addresses into the "BCC" field of the message you're composing, or import them into your mailing list service (Constant Contact, MailChimp, etc.).
• It does NOT allow you to have multiple lists. You can place as many signup form blocks as you want on your site, but they all submit to the same list.
• It does NOT provide any other form fields besides email address. You cannot collect people's names, addresses, favorite color, etc. -- only email address.

If you are looking for these things, try Tony's full-featured Mailing List Add-On instead.

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UPDATE 1.01 - Fixed a bug that was causing successful signups to always be redirected to the home page, even if the block was on a different page (thanks @orange73). Also added more helpful database error messages when the site is in development mode (thanks @websitehebben).

UPDATE 1.02 - Fixed problem with version numbers, so now the dashboard won't keep telling you there's an update available even after you've updated.

UPDATE 1.03 - The "confirm signup" single page is now excluded from nav by default when the package is installed.
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HOW TO CUSTOMIZE FORM STYLES:

Look at the YOURSITE/packages/email_list_signup/blocks/email_list_signup/view.css file to see all of the styles that can be configured for the form. You can override any of these by copying and pasting them into your theme's stylesheet and changing them there.

HOW TO DISPLAY ERROR/SUCCESS MESSAGES ANYWHERE ON THE PAGE:

Error and success messages can either be displayed in the block itself (the default option), or anywhere else on your page. To display messages elsewhere on your page, you need to uncheck the "Display Messages In Block?" box when you add/edit the form, AND you need to add the following line of code to your theme's page type templates in the place you want messages to appear:

<?php Loader::packageElement('page_messages', 'email_list_signup'); ?>

HOW TO CUSTOMIZE EMAIL TEMPLATES:

Copy any of the files in the YOURSITE/packages/email_list_signup/mail/ directory to YOURSITE/mail/ and make changes there.