Example - SMTP Logs
The following logs show the situation when IceWarp Server connects to some host (e.g.: host of remote account, backup domain, etc.) and cannot resolve the host's IP.
SYSTEM [1ABC] 11:24:33 Client session Connecting to 'mail.hsps.com.br'
SYSTEM [1ABC] 11:24:36 Client session Could not connect to 'mail.hsps.com.br(0.0.0.0)'
SYSTEM [1ABC] 11:24:36 Client session Disconnected
Solution
Understand why the DNS cannot resolve this name (System - Connection - DNS Server), or allocate a free DNS temporarily (openDNS).