Add-Ons
Add awesome features to WP Email Manager
Please refer to this article.

Custom Server Configuration
Free
If you would like a particular site in a multisite installation to use a different email server from the rest of the network, this addon will facilitate that.

Domain Manager
$39 - $149
Enable users to add their existing domains to your email server while restricting domain tlds in order to facilitate email account management.

Frontend Addon
Free
The Frontend Addon enables you to manage email accounts on the frontend of your website. It integrates with the WooCommerce Addon and WP Ultimo.

WooCommerce Addon
$39 - $149
The WooCommerce Addon enables you to sell email accounts using WooCommerce plugin per domain. It integrates with WooCommerce Subscriptions & Sumo - WooCommerce Subscriptions.