Finding the best SMTP server provider for Flowster workflows

Reliable email delivery can make automated business workflows much smoother. I’m exploring SMTP options for Flowster workflows that handle notifications, customer updates, and other automated emails.
When comparing a best SMTP server provider, I’m mainly looking at deliverability, reliability, authentication, and ease of integration. I came across SMTPmart while researching different options and would be interested in hearing how others handle email automation. What factors matter most when choosing a best SMTP server provider for a workflow-based setup?