MailUtl3 User's Manual

Copyright (C) 2002- Fumio Kawamata

Last updated on May 25, 2008

Japanese page is available.

Permission is granted to copy, distribute and/or modify this document titled "MailUtl3 User's Manual" under the terms of the GNU Free Documentation License Version 1.2 published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.

1. About the MailUtl3

The MailUtl3 is a sort of the POP3 proxy programs. The MailUtl3 receives your mail client's command, transfers it to the actual POP3 server, receives its response and transfers it to your client. The MailUtl3 relays commands and responses. The MailUtl3 adds several information in the mail header and this respect is a different point against the usual proxy programs.

Please see the POP3 proxy page if you want to know about the MailUtl3 as a POP3 proxy.

The MailUtl3 can identify some kind of e-mails by using the S25R system which is a brainchild of Mr. Asami Hideo. Please see his web page at if you want to know what the S25R system is and what the efficiency is.

2. How to install and uninstall

Before you unzip the distribution package, decide the directory where you want to install the MailUtl3. The directory where you unzip the distribution package will become the install directory. The MailUtl3 does not have an installer.

Delete all files in the directory if you want to remove the MailUtl3. The MailUtl3 does not have an uninstaller. You must delete the MailUtl3 manually by yourself.

3. How to set up

Background knowledge

The author will explain the background knowledge required when you use the MailUtl3. Plese see How to inform the server information into the MailUtl3 page first.

Set up

After you understood how to inform the server information into the MailUtl3, please read Making of the configuration file.

After you made a configuration file, please read MailUtl3 settings.

In the next step, it is time to set up your mail client. The author wrote explanations for serveral mail clients.

4. How to run and terminate

Firewall warning dialog willl be displayed when you run the MailUtl3 at the first time. So, please see Firewall warning before you will run the MailUtl3. Execute the MailUtl3 prior you execute your mail client. The mail icon will be revolving while the MailUtl3 transfering the commands and responses.

The MailUtl3 inserts the following fields in the header part.

Terminate the MailUtl3 by following procedure.

  1. Display the main form by left or right click of the mouse button on the post box icon.
  2. Select [File|Exit/Terminate] menu item.

5. Technical information

Please see the Flow diagram page if you have an interest of the flow diagram among the mail client, MailUtl3 and actual POP3 server.

Please see the Network traffice and DNS server's resource consumption page if you have an interest about the increase in amount of the network traffic and DNS server's resource consumption caused by the MailUtl3.

The MailUtl3 relays STAT, LIST, RETR, DELE, RSET, QUIT, UIDL, USER and PASS commands. The MailUtl3 replies "+OK" against the NOOP command, but the MailUtl3 does not transfer it to the actual POP3 server in current version.

The program was written by Delphi language (Delphi 6 Professional). The author used the Indy Version 10.1.6, DevSnapshot on January 19th 2007.

6. Copyright notices

Classification of the works

The works which compose the MailUtl3 are classified into two. The works where Fumio Kawamata has the copyright and the works where other persons or groupes have the copyright.

The works where Fumio Kawamata has the copyright

Currently, the author does not release source program files by several reasons. The MailUtl3 will be listed at Fumio Kawamata's Open Laboratory ( That means you will obtain the source code. Please wait until then if you want to know inside of the MailUtl3. The source program files will be distributed under the GNU GPL verion 2.

The works where other persons or groups have the copyrights

7. Contact address

Please send e-mail to if you have any question about the MailUtl3 or this document. However, the author do not read several kinds of e-mails such as in below.

The author is just a hobby programmer. The author writes program codes and documents in the weekend. The activity is low. Please do not expect the author's quick response.

8. References

  1. Indy documents and a lot of articles in the Indey news groups.
  2. RFC 1939 (Post Office Protocol - Version 3)
  3. RFC 2449 (POP3 Extension Mechanism)
  5. Using Norton Antivirus (NAV) with POPFile
  6. DNS & BIND 4th edition. ISBN4-87311-074-2