Tips for troubleshooting email performance.
I have a CiviCRM instance that currently sends 800 emails an hour and I have the feeling that it can do better. Some details.
- CiviCRM 5.51.3
- The CMS is Drupal 9.
- The mail is sent by SMTP to AmazonSES (The Paris data-center is used, and port 587)
The cron starts 4 times per hour. So, it is ready for 2000 emails.
The mailing process keeps the server busy. There is a long-running PHP process that asks 25% processor time, and MySQL needs 15%.
The SMTP server sometimes emits the following error.
(code: 451, response: 4.4.2 Timeout waiting for data from client.)]
This suggests that Amazon is fast enough and waits for CiviCRM. It also bothers me a bit, and that is why the database update rate is 1 (to prevent double emails).
The sending limit for Amazon is 50 mails a second (with a maximum of, 100000 a day).
Has someone tips, how to troubleshoot this? I already disabled the custom tokens, unfortunately without impact.