i was paying for sendgrid ($20/mo) + mailchimp ($45/mo) + a zapier plan ($30/mo) to glue them together + probably 5 hours/month of my time maintaining it all.
for a micro saas doing maybe 15k emails a month, this was ridiculous. auth emails went through sendgrid, marketing through mailchimp, and zapier connected database events to both.
finally consolidated everything into a single tool that connects directly to my postgres database. one place for auth emails, transactional, onboarding sequences, broadcasts - everything. $16/month.
the lesson: if you're early stage, you probably don't need three separate email tools. look for something that handles all email types from one platform.