MailChimp - MailChimp is the best way to design, send, and share email newsletters.
WHMCS - WHMCS is an all-in-one client management, billing & support system for online businesses.
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
HostBill - HostBill is a powerful and flexible, all-in-one automation, billing, client management and support platform for online businesses.
Campaign Monitor - Email marketing software built for designers and their clients to run successful email campaigns.
Blesta - Blesta is professional client management, billing, and support software.