Zimbra stopped sending or recieving email quite suddenly. Trying to send an email via the web, results in a "server appears to be slow" popup box with a "network server error" popup describing it is unable to send a message. All email sent to us is being bounced back as undeliverable.

All services seem to be running when zmcontrol status is reqested (except for stats which hasn't worked in a year).

Can anyone tell me where I should start looking for trouble?

Thanks much