Email send results in 503 error

Running on ver 1.4.3
When I want to send an invoice, I click on the option to “send email” - this brings up the email form with the little airplane send button. When I click that button I ALWAYS get a 503 error on first click. If I click again, the email is sent successfully.

I’ve checked my server error logs and there is nothing logged for this event.

Any ideas what I can do to fix this?
(Running on a LiteSpeed server if that makes any difference)

You can change the logging behaviour in the config file. It’s called log threshold and should be set to 2 in your case.
The logs will be saved in your webserver error logs and the internal logs which can be found in application/logs