When configuring the SMTP "Retries" parameter, when are emails retried?

[nkosi23]

When configuring the SMTP "Retries" setting, when are emails retried? Is it instantly, or is there some sort of exponential backoff?

Some recipient email servers defer messages and - for example - require the sender to try again in 5 or 15 minutes, so I am wondering if this setting could do the trick.

I've spent some time looking at the source code but failed to find the part dealing with retries.

[knadh]

It's instantly using a different connection from the pool. There's no system to record and defer a sending currently.

[nkosi23]

Thanks