Moved into a comment per feedback

.env.production.sample

@@ -26,7 +26,8 @@ OTP_SECRET=
 # EMAIL_DOMAIN_WHITELIST=example1.com|example2.de|etc
 
 # E-mail configuration
-SMTP_SERVER=smtp.mailgun.org, smtp.sparkpostmail.com, etc.
+# Note: Mailgun and SparkPost (https://sparkpo.st/smtp) each have good free tiers
+SMTP_SERVER=smtp.mailgun.org
 SMTP_PORT=587
 SMTP_LOGIN=
 SMTP_PASSWORD=