Case Study: ChatWork achieves 100x faster, real-time email delivery and zero email-management time with SendGrid

ChatWork delivers in Japan with Twilio SendGrid and KKE

ChatWork, Japan’s leading business chat platform serving 141,000 companies in 205 countries, relied on email notifications to keep users engaged. Rapid growth—peaking at 400,000 emails a day—exposed limits in their previous provider: rising server costs, hours-long delivery delays, and some messages never reaching inboxes, forcing engineers to spend significant time troubleshooting.

In three months ChatWork migrated to SendGrid’s SMTP API with support from Kozo Keikaku Engineering, warmed IPs, and began using SendGrid’s Webhook API to monitor deliverability. The change enabled real-time, scalable sending with built-in deliverability features, producing 100x faster delivery and eliminating engineering time spent on email while restoring reliable, cost-effective delivery.

ChatWork

Masaki Yamamoto

CTO