Connections

Network connections are established to and from the ISMail SMTP server in order to receive and send messages. ISMail groups all connections made to the SMTP server as 'Incoming' connections and all connections originating from the SMTP server as 'Outgoing' connections.

Outgoing connections can be restricted using the 'Smarthost' option.

SmartHost

Normally, ISMail will send messages directly to the mail server of a recipient. A 'SmartHost', however, can be used to relay all messages to another mail server in order to workaround problems with firewalls, resolve outgoing port restrictions (port blocking), or to insure message delivery to mail servers which place various restrictions on senders (e.g. disallow dynamic IPs, use reverse IP lookups).

Note: port blocking can be tested by opening a DOS window and entering 'telnet instantservers.com 25'. If an SMTP 'welcome' message appears, then port 25 is not blocked (enter 'quit' to exit this connection). If, however, a connection is not established, then port 25 may be blocked. Futher testing should be done to determine the cause of the failed connection.

Adding A SmartHost

To add a SmartHost (using standard port 25):

1. On the 'Connections tab, select the SmartHost checkbox.
2. Enter the name or IP address of the SmartHost.
3. If all messages should only be sent using the SmartHost, select the 'Use SmartHost Exclusively' box. If messages should be sent using the SmartHost only if direct sending fails, deselect the 'Use SmartHost Exclusively' box.
4. If the SmartHost requires authentication, select the 'Authenticate' box and enter an 'Account Name' and 'Password' for an account existing on the SmartHost.
5. Click 'Apply'.

To add a SmartHost (using a non-standard port):

1. On the 'Connections tab, select the SmartHost checkbox.
2. Enter the name or IP address of the SmartHost, followed by a color (':') followed by the port number (e.g. example.com:27 would use host 'example.com' on port 27).
3. If all messages should only be sent using the SmartHost, select the 'Use SmartHost Exclusively' box. If messages should be sent using the SmartHost only if direct sending fails, deselect the 'Use SmartHost Exclusively' box.
4. If the SmartHost requires authentication, select the 'Authenticate' box and enter an 'Account Name' and 'Password' for an account existing on the SmartHost.
5. Click 'Apply'.

Outgoing Connections (min: 1, max: 20, default: 2 connections)

The maximum number of ISMail outgoing connections active at any time may be specified. A value of 1 will force outgoing messages to be sent serially, one at a time. A larger number may be used so that a slow connection (or a large message) does not block other messages from being processedat the same time.

Setting the Maximum Outgoing Connections

1. On the 'Connections tab, under 'Outgoing', enter the maximum number of outgoing connections.
2. Click 'Apply'.

Incoming Connections (min: 10/1, max: 100/10, default: 20/5)

The maximum number of ISMail incoming connections active at any time may be specified. The maximum number of ISMail incoming connections from any single host (IP) active at any time may also be specified. If a particular mail server is placing a large load on ISMail, the maximum number of incoming connections from any single host can be set to 1 to reduce this load. A larger number may be used so that a slow connection (or a large message) does not block other messages from being processed at the same time.

Setting the Maximum Incoming Connections:

1. On the 'Connections tab, under 'Incoming', enter the maximum number of incoming connections (Total)
2. Enter the maximum number of incoming connections from a single IP (From a Single Host).
3. Click 'Apply'.