PC Ext: How External Picks Up Mail (199800)


The information in this article applies to:

  • Microsoft Mail for PC Networks 3.0
  • Microsoft Mail for PC Networks 3.2
  • Microsoft Mail for PC Networks 3.2a
  • Microsoft Mail for PC Networks 3.5
This article was previously published under Q199800

SUMMARY

This article describes the process that External (message transfer agent [MTA] for Microsoft Mail) goes through when picking up mail from a Microsoft Mail Postoffice.

First you must have a good understanding of what an .xtn file is. There is one .xtn file for each Microsoft Mail Network that your postoffice has access to. So, assuming you have networks named Net1 and Net2, you would have an .xtn file for each of these. Inside the .xtn file, you find a list of all the postoffices in that network.

Each of these networks has a hexadecimal ID assigned to it and the .xtn file is named with the hexadecimal ID. To find the hexadecimal ID of a particular network, the External program must look in the Network.glb file.

MORE INFORMATION

So, with this basic understanding, the process works as follows: External looks into the Network.glb file and gets a list of all .xtn files. It reads the first .xtn file in numerical order, then reads the first postoffice mailbag within the .xtn file, and performs the following calculation:

If there are less than 5 messages, deliver now.
If there are more than 50 messages, deliver now.

Example 1

External looks into the Network.glb and finds that Net1 has an XTN value of 00000001. It then reads that file and finds that Net1 has three postoffices: POA, POB, and POC. It reads the hexadecimal ID for the POA mailbag and finds there are three messages. It picks up these messages, reads the hexadecimal ID for the POB mailbag, and finds there are 10 messages. It leaves those messages in that queue, reads the POC mailbag, and finds 15 messages. It then sees that it has room to pick up mail from all postoffices, and sends a total of 38 messages (3+10+15=38). After all messages are sent from this .xtn file, External goes to the next .xtn file or gateway definition.

Example 2

External looks into the Network.glb and finds that Net1 has a hexadecimal ID value of 00000001. It then reads that .xtn file and finds Net1 has three postoffices POA, POB, and POC. It reads the hexadecimal ID for the POA mailbag and finds there are 50 messages. It picks up these messages and ignores the other postoffices until the next cycle. After all messages are sent from this .xtn file, External goes to the next .xtn file or gateway definition.

Example 3

External looks into the Network.glb and finds that Net1 has a hexadecimal ID value of 00000001. It then reads that .xtn file and finds Net1 has three postoffices POA, POB, and POC. It reads the hexadecimal ID for the POA mailbag and finds there are seven messages. It ignores these messages and reads hexadecimal ID for the POB mailbag, and finds there are four messages. It picks these up, reads the hexadecimal ID for the POC mailbag, and finds 75 messages. It sees that it has room to pick up 43 of these messages for delivery. External then sends a total of 50 messages (7+43=50). After all messages are sent from this .xtn file, External goes to the next .xtn file or gateway definition.
Modification Type:MinorLast Reviewed:7/16/2004
Keywords:kbhowto KB199800
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