How to send email faster?

Question

Exim

There is an email newsletter, the problem is that letters are sent indecently for a long time (1+ seconds per recipient). Tried both through smtp and through sendmail directly, everything is the same. How to optimize this business? How to send mail to sendmail without waiting for a response? Emails are generated very fast using the null transport, 0.003 sec per 500 emails. The whole plug is in sending.

Answer 1

use ssmtp on a distributed cluster