PostCast SMTP Server
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Host Name

This value depends on whether you want the program to accept connections only from the computer on which it has been installed, from the Internet, or from a LAN.

If you want to connect to the server only from the computer on which it has been installed, enter "localhost" or "". To be able to access the program from the Internet, enter the Internet IP address of the computer. To access the program from the local network (LAN), you should enter the IP address of your network adapter or the computer name. This means the IP address under which the computer on which the program has been installed is recognized in the network.

If you are not sure what exactly is your Internet IP address or your local, LAN IP address, press CRL+I on your keyboard or select "Show network configuration" from the "Tools" menu. To find out your Internet IP address, you must be connected to the Internet. You can also use the web site to get your Internet IP. If you enter "localhost" or "" as "host name" value, the program will accept connections only from the same computer. No other computer in the network or from the Internet will be able to gain access to it.

The situation is somewhat different when you enter the local or Internet IP address. In that case, it is possible to connect to the program not only from the same computer but also from all the computers in the network or from the Internet. If you enter the local IP address, you rule out the possibility of connections from the Internet. When you enter the Internet IP address, direct connections with LAN are not possible. In that case, computers from LAN will be able to connect to the program if they have the Internet connection. When the Internet IP address of the computer on which PostCast Server is installed is entered in the e-mail program settings of the SMTP server, users from other computers in the LAN will be able to send messages through it.

Server Port

Usually, you will need to change the port number only in case the port number 25 on your computer is occupied by some previously installed server program. If that is the case, PostCast Server will report the problem and suggest using the next free port on your computer.

If no other server program on your computer is using port number 25, you do not need to change this value. Port 25 is a default value both for the server and the e-mail client. If you change the port number in the Server Port text box in PostCast Server,   do the same in the settings of all e-mail programs you use, otherwise they will not be able to establish the connection to the server.

DNS Server Address

When PostCast Server tries to send a message to a recipient the domain name in the e-mail address is translated into the address of the server that receives messages for that domain. The DNS server is used by the program to find correct addresses of different servers on the Internet. For instance, the DNS server turns "" into, which is the IP address of "".

Sending speed is highest if you use your ISP's DNS server. To find out which DNS server address to enter, you should consult the documentation and instructions on connecting to the Internet that you have received from your ISP. If you do not have the documentation, you should be able to find DNS server addresses on your ISP's web site. The Professional Edition of the program is able to cache all DNS requests locally.

While connected to the Internet, you can click on the "Detect" button and the program will automatically enter the value of the currently active DNS server. Select the "Show network configuration" option from the "Tools" menu and the program will, apart from the DNS server address, display your local and Internet IP address as well.

DNS port

Default DNS port is 53, but you can change this value if you want the program to use the DNS server that works on a non-standard port (any port number between 1 and 65535).

Detect when default DNS addresses change

This option allows the Professional Edition of PostCast Server to automatically configure correct DNS server addresses when you switch to a different Internet connection. This is especially useful if you are using connections with several ISPs.

Use DNS caching to speed up sending

An easy way to speed up sending is to cache DNS information locally thereby eliminating the need for repetitive queries to the remote DNS server. This is done by telling PostCast Server to contact a local database on your computer, rather than the remote DNS server. This local connection can be performed much faster and does not depend on the response time of the remote DNS server across the Internet. For more information, see this page.

Mail sending frequency

Depending on its settings, the program will send the downloaded messages in regular time intervals, immediately after downloading them, or manually by clicking on the "Start" button in the toolbar.


After receiving any message from the e-mail client, the program will automatically start the sending process. As it receives messages, they are immediately delivered to their destination without any delay. At the end of each sending process, the program will take a several-minute break. The break can last from 0 to 90 minutes.


When the program receives messages from the e-mail program, they are left waiting in the Outbox until you click on the "Start" button in the main toolbar, press F5 on the keyboard, or select the "Start" option from the "File" menu.


The messages in the Outbox folder are delivered every hour. It is possible to specify the number of minutes after full hour when you want the program to start the delivery.


The messages in the Outbox folder are delivered once a day at a specified time. When you click on the "More Options" button, you will be able to specify the exact day in a week when you want the program to send your messages.

Just once

The program will start sending messages on a specified day and at a specified time.

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