The SMTPGate is a CommuniGate communication module supporting e-mail message transfer using the SMTP Internet protocol (RFC821) via TCP/IP network.
The SMTPGate module supports multi-stream communications and can send messages to and receive messages from several other hosts simultaneously.
The SMTPGate module can work together with POPGate module providing complete TCP/IP Internet e-mail services.
The SMTPGate module can work together with UUCPGate module providing both TCP/IP and UUCP Internet e-mail. The CommuniGate Router takes care of directing messages to the proper gate.
The SMTPGate module can use an external, "foreign" mail server (the mode most of other Macintosh e-mail packages use), or it can deliver messages directly, using the DNR services.
When a foreign mail server is used, SMTPGate connects to it and sends all messages from its queue to that host. Since the mail server host is usually a host on the same network, messages are sent quickly. But this method can cause additional delay in message delivery, since messages are queued on the foreign server and those queues can be rather long. Using Foreign Mail Server method is recommended when your server is connected to Internet via dial-up lines (using PPP or SLIP protocols) and you want messages to leave your server as soon as possible to keep the connection time short.
The DNR (Domain Name Resolver) method is one used in "real" mail systems. For each message and address in its queue, SMTPGate uses DNS (domain name servers) to get the name and address of the host to send the message to. It can be the destination host itself, or some relay host. The information about the proper relay host is stored in so-called MX records on Domain Name Servers. For each destination host several records can exist, each record having a priority value. If the relay host with the highest priority is not answering, other MX records are used and other relay hosts are tried. If no relay host is available, the message remains in the SMTPGate queue, and the next attempt to deliver it is made later.
This method allows to deliver a message either directly to the recipient computer or to a relay host that is "very close" to the recipient computer. Recipients can read your messages almost immediately, and your messaging system does not rely on some "foreign mail server" performance.
Unfortunately, the "Get MX" function is not properly implemented in MacTCP, so the DNR method is disabled when the regular MacTCP is installed. The Open Transport TCP does implement DNR functions correctly, and it is under testing now. The "Using Open Transport DNR" option will be enabled for OT-equipped servers in the next release of the SMTPGate.
Installation
Place the SMTPGate module into the Modules folder inside the CommuniGate Folder in your System Folder. If you use a MacPPP link to Internet, make sure the TCP Agent applet is placed in the Modules folder, too. Restart the CommuniGate Server.
Configuring
After the SMTPGate module is placed in the Modules folder on the Server computer, you can configure it from any workstation that has the "can configure" privilege.
1. Choose SMTPGate from the Monitor section of the Server menu. The SMTPGate Monitor window appears.
2. Choose "Service Settings…" from the SMTPGate menu. Enter the mail server domain name if you plan to use the "foreign mail server" option (usually, it is the domain name of your network provider host).
3. Set the "Max concurrent sends" option. This option limits the number of SMTP connections the SMTPGate can make at the same time. If you use a foreign mail server, you can set this option to 1.
4. Set the "Max concurrent receives" option. This option limits the number of incoming SMTP connections the SMTPGate can accept at the same time. Other hosts will connect your host via SMTP if your systems acts as a real SMTP mail server. If you use a network provider, consult with them if you can get your mail via SMTP.
If mail comes to your CommuniGate Server via UUCP only or if you have to use a foreign POP server(s) to get your mail, set the "Max concurrent receives" option to zero.
5. You may want to use the "Mail coding" option to make the SMTPGate convert message texts from the Mac OS coding to the coding used in your national network. Remember that some mail hosts still support the standard ASCII character set only (7-bit data), so national symbols will be lost when mail comes through those hosts.
6. Set the log level.
Note: if you select the "All Info" log level, log files will become very large very soon and the system may operate slowly when a SMTP connection is active.
Troubleshooting
If you see that the SMTPGate tries to connect to a host, but fails, or it cannot negotiate with that host, switch the log level to "Low-Level Info" or "All Info". After the next attempt, switch logging back and examine the log. If you still cannot find the source of the problem, and the administrator of that host cannot help either, copy that part of the log and e-mail it to support@stalker.com with the detailed description of the problem as you see it. Include the information about the versions of your CommuniGate Server and SMTPGate (use the About CommuniGate command from the Apple menu in the CommuniGator application).
Attachments
The SMTPGate converts all attachments on the fly into the BinHex format while sending the message. It also detects the BinHex enclosures in the incoming messages and converts them into the attachments. If conversion fails, the unmodified original BinHex text is included in the message body.
Routing
The SMTPGate module is always used as the link to the "rest of the world". i.e. if a message cannot be routed to other modules, and the domain name of the recipient contains dots, the message is routed to the SMTPGate.
The SMTPGate module recognizes the domain "[xx.yy.zz.tt]", where xx.yy.zz.tt is the IP address of your machine, so your system can accept messages even if they were sent using the [xx.yy.zz.tt] notation rather than domain names.
Revision History
1.2
* Dial-up links are supported now, the "Sleep Time" option is gone.
* Addresses in form of ip-addresses [xx.yy.zz.tt] are processed properly now.
* Error reporting is improved.
* Bug that caused failures with the -43 error code is fixed
1.1
* The "Sleep Time" option is implemented to support dial-up links.
* Internal changes to allow the SMTPGate to work with Open Transport TCP/IP.
1.0.3
* MacTCP session closing procedure has been changed to improve stability.
* MAIL From: command generating is fixed to avoid "From address rejected" errors.
1.0.2
* MacTCP access scheme has been changed to improve stability and to fix the
problem that resulted in connection failures for various hosts.
1.0.1
* Fixed the Network Coding processing: when this option was set to None, messages
were decoded using a table that did not exist in reality.
