If the server is not permanently connected to the Internet (it operates in the offline mode), you can set server to send messages immediately:
If this option is checked, the message queue is cleared every time a new message is added, in correspondence with the following rules:
any priority — anytime a message of any priority is added, the queue is cleared completely.
high priority — anytime a high priority message is added, the queue is cleared completely.
This option allows automatic initiation of a dial-up connection in case that the server received either a high-priority message or a message of any priority (depending on the settings described above). Therefore it is recommended to set this option only if the Send messages in outgoing queue when server receives a new mail with option is enabled.
The recommended configuration is described below (see figure 11.2 Sending High Priority Messages tab):
Check Send messages in outgoing queue when server receives a new mail with.
Select high priority.
Check Allow to establish dial-up connection if necessary.
This configuration specifies that every time a high-priority message is received and added to the queue, the connection gets dialed and the queue gets sent immediately upon the successful connection.