Hi everyone,

Sitting with an issue and hoping someone has some advice. We have a user where normal email sending works. But, when an email is sent to a large group and they click send, the circle button appears and after around 4 - 5 minutes the error 'connection error [failed to reach server]' is presented.

On the email server that's hosting the email account, Exim reports the following error 11 minutes later after the web server (Apache / fpm) timeouts, which are set to 600 seconds, on the Roundcube server are reached:
--------------------------------------------------------------------------------------
2024-07-23 10:18:04 unexpected disconnection while reading SMTP command from redacted-hostname (redacted-hostname) [Redacted-IP-address] D=11m29s

--------------------------------------------------------------------------------------

Apache error log:
--------------------------------------------------------------------------------------
[Tue Jul 23 10:16:34.366746 2024] [proxy_fcgi:error] [pid 1170321:tid 1170362] (70007)The timeout specified has expired: [client REDACTED] AH01075: Error dispatching request to : (polling), referer: https://REDACTED/?_task=mail&_action=compose&_id=4318354025669f63d117867

--------------------------------------------------------------------------------------

All web server / PHP related timeouts are set to above 300 seconds. All settings in the Roundcube configuration related to timeouts look okay.

Any advice on what more can be checked will be appreciated.

Thanks!

Stephan