Customer.io Newsletter is Customer.io's product line for email and message automation, founded in 2012 in Portland, USA, using an event-driven engine and visual customer journeys to send personalized emails and push based on real user behavior.
ActiveCampaign Newsletter is ActiveCampaign's email marketing product line, founded in 2003 in Chicago, USA, combining visual automation workflows, behavior triggers, and multichannel reach for 180K+ business customers.
SendPulse Email is the email sending component of the SendPulse platform, offering SMTP/API email delivery with a permanent free daily allocation, suited for budget-conscious SMB email marketing needs.