wp.insider

smp7

This addon allows you to specify a MailChimp list name for each of your access levels. When members join your site, they get signed up to the specified MailChimp list.
This addon requires the <a href="https://wordpress.org/plugins/simple-membership/" rel="ugc">simple membership plugin</a>.
After you install this addon, edit your membership level and specify the mailchimp list name. Then go to the MailChimp settings interface and specify your API Key.
Read the following page for step by step usage documentation: 
https://simple-membership-plugin.com/signup-members-mailchimp-list/

Simple Membership MailChimp Integration

An addon for the simple membership plugin to signup members to your MailChimp list

affmngr

This addon allows you to specify a MailPoet Newsletter list name in the addon settings.
When affiliates join your site, they get signed up to the specified MailPoet Newsletter list automatically.
This addon requires the <a href="https://wordpress.org/plugins/affiliates-manager/" rel="ugc">Affiliates Manager Plugin</a>.
After you install this addon, go to the MailPoet Newsletter settings interface and specify your MailPoet Newsletter list ID and save the settings.
Read the following page for step by step usage documentation: 
https://wpaffiliatemanager.com/sign-affiliates-to-mailpoet-list/

Affiliates Manager MailPoet Integration

An addon for the Affiliates Manager plugin to signup the affiliates to your MailPoet Newsletter list

Simple Membership MailChimp Integration vs Affiliates Manager MailPoet Integration