March 2022 Summaries

The author discusses how Postmark, an email service provider, needs to increase its capacity to handle growing demand. The current system has limitations due to physical constraints, such as the capacity of direct connect (DC) connections and load balancers. To address this, the team upgraded their DC connections from 1Gbps to 10Gbps links, which improved performance but still had limitations due to other parts of the system, including firewalls with limited bandwidth. The author is now exploring new solutions, such as upgrading firewalls, to further improve capacity and performance. Despite these challenges, Postmark has seen significant growth in email volume and customer support, and the team is committed to delivering fast and reliable email services.

Postmark is a developer favorite due to its easy integration, reliable delivery, and comprehensive feature set. It offers a volume-based pricing model with no feature gates or paywalls. In contrast, SendGrid is an older player in the email API space that provides a broad range of services beyond just an API, but has received mixed reviews regarding customer service quality. SparkPost is a popular choice for Enterprise customers due to its focus on security and compliance, while Mailgun's API is powerful and flexible but lacks official libraries in some languages. Amazon SES is the cheapest email API service with limited features and a stripped-down service, making it less suitable for most use cases.