nodemailer gmail connection closed with high number of mails

Question

I have exactly the same issue as this post : Send multipe emails using nodemailer and gmail

When sending too many emails with nodemailer and gmail, I get a 421 error

Answer 1

Use Pooled SMTP : https://nodemailer.com/smtp/pooled/

If pooling is used then Nodemailer keeps a fixed amount of connections open and sends the next message once a connection becomes available. It is mostly useful when you have a large number of messages that you want to send in batches or your provider allows you to only use a small amount of parallel connections.