OAuth2-enabled email proxy application

O2Popper User’s Guide
Windows Versionfor Version 3.0.1 (Build: 2022-12-26)

MURATA Yasuhisa
NIPS Technical Division

Introduction
This application was developed for the purpose of enabling continuous
use of mail software and systems that do not support OAuth2.
There are also erroneous transmission prevention functions.
I hope you can use it.

2Notice
To use this application for the first time, it is now necessary to obtain“Client ID” and “Client Secret” for OAuth2. (The one prepared by theauthor is because the limit of 100 free users has been reached.)

Please refer to “How to get Client ID and Client Secret” on the websiteof this application.

Note:
Accounts belonging to the same organization as the author
are not eligible.

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Contents

1. Environment
2. Installation
3. Options
4. New functions

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Environment
I have confirmed the operation on Windows10.
It may not work on Windows 7 or earlier.

I have confirmed that it works in combination with the following mail clients.
••••

Outlook 2016
Thunderbird
SylpheedEdMax

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Installation

6You can download the installer from the following URL.

https://www.nips.ac.jp/~murata/o2popper/downloads/

Note: If the file is deleted due to false detection by security software, please restore it.

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Then double-click the downloaded installer to run it. At this time, if a warning screen like the one on thelower left is displayed, click “More info” and then click the “Run anyway” button.

8If the following warning screen is displayed, click the “Yes” button.

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When the installer starts normally, the following screen will be displayed.
Follow the instructions on the screen.

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If you check “Create a shortcut at startup”, this application will be started automatically when you sign
in to Windows. If you do not want to start automatically, uncheck it.

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When this application is started normally, the icon of this application will be displayed in the task tray
(system tray) at the bottom right of the screen.

17You need to make the initial settings first.
Click the icon of this application to display the menu. Select “Settings...” in this.

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The setting screen is as follows.

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If you prepare the “Secret File” for OAuth2 yourself, specify the file as follows.

You can also enter “Client ID” and “Client Secret” directly as follows.

If you want to use the “Secret File” prepared by the author, leave it as “Built-in”.

When authorizing OAuth2, if you use the “Secret File” prepared by the author,“Google hasn't verified this app”
may be displayed.
20Enter your email address and click the “Auth...” button.

Note: If you check “Send login_hint”, you can skip the"Choose an account" screen that appears after this.
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The OS standard web browser starts and the Google account authentication screen is displayed.

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If the following screen is displayed after the Google account has been authenticated, click the“Advanced” link.

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After clicking the “Advanced” link, click the “Go to O2Popper (unsafe)” link at the bottom of the screen.

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If the following screen is displayed, click the “Allow” button.

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If the following screen is displayed, click the “Allow” button.

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If “Authorization” is successful, the web browser will display the following screen.

If “Authorization” is successful, this application will display the following screen.

If you close the web browser in the middle of “Authorization”, control will not return to this application.
In this case, start the web browser again and access the following URL.
http://localhost:8080
An error will occur, but control will return to this application.
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When “Authorization” is completed, click the “OK” button to close the setting screen.

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Next, set up your email client (Outlook, Thunderbird, etc.) as follows.

Incoming Mail (POP) Server

localhostRequires SSL: No
Port: 8110

Outgoing Mail (SMTP) Server

localhostRequires SSL: No
Port: 8025

Account Name, User Name, orEmail addressYour email address

Password

Appropriate string
Note: Not used for authentication.

Note: If the above port number is used by another application, change it to another valueon the setting screen of this application, and change the value of the mail client
according to this application.

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Outlook configuration example:

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Thunderbird configuration example:31

If you want to receive emails by POP, please enable POP on Gmail side.

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After completing the settings of the mail client and Gmail, select “Monitor...” from the menu of thisapplication.

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Click the “Start” button on the monitor to start receiving SMTP and POP.

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Start sending and receiving email client. If the output is as follows, it is successful.

When received by POP:

When sent by SMTP:

Note:
Lines with purple text starting with "<<<" are the responses from Gmail's POP and SMTP servers.
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If it does not work, there may be a problem with the settings on the security software side.
The settings for sending and receiving between this application and the Gmail server are as follows.

Incoming Mail (POP) Server

pop.gmail.com
Port: 995

Outgoing Mail (SMTP) Server

smtp.gmail.com
Port: 465

Make sure that the security software has not blocked the communication or modified thecommunication contents.
If you cannot solve the problem, I recommend that you consult with a detailed person near you.

The compatibility between the mail client and this application may be poor.
You cannot use a mail client that outputs protocol commands in an order not expected by thisapplication. I would appreciate it if you could let the author know.
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Close the monitor when you have successfully sent and received emails. (Reception is stopped whenthe monitor screen is closed.) If you want to start receiving automatically when this application starts,
change “Initial State” in “Listen” on the setting screen to “Start” and click the “OK” button.

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Select “Start” on the menu screen to start receiving.

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Options

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There are erroneous transmission prevention functions. Please adjust on the “Block SMTP” tab of thesetting screen.

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To+Cc Max:
Specify the maximum total number of addresses that can be specified for To and Cc of thedestination. If this value is exceeded, it will not be sent as an error. Set to 0 for unlimited. It wasimplemented to prevent accidents in which Cc and Bcc are mistakenly transmitted in large
quantities. Specify the addresses you do not want to be included in the address count in the"Exclude" field.
Note: Names containing “@” may be counted excessively.
Note: If a substring of the address is specified in the “Exclude” field, it will be judged as a suffix
match. It is not case sensitive.
You can specify multiple conditions by separating them with a single-byte space or a single-bytecomma (,).

Send Delay:
You can cancel the transmission within the specified number of seconds. You canspecify up to 30 seconds, and if you set it to 0, it will be sent without delay.
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Remove X-Mailer/User-Agent header:
If checked, the X-Mailer header and User-Agent header will be deleted before sending.
If you do not want the other party to know the type and version information of the email
software you are using, please check it.
Change Envelope-From:
If checked, the Envelope From will be changed to the email address used for OAuth2
authentication and sent. If the sender of the email is a group address, problems such as"cannot post" or "error email does not arrive" may occur.
This is a function to avoid such problems.
Block list:

Please specify the address you want to block sending.
If a substring of the address is specified, it is judged by a suffix match.
It is not case sensitive.
You can specify multiple conditions by separating them with single-byte spaces, singlebyte commas, and line breaks.
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New functions43

From version 3.0.0, you can set multiple accounts.
If you pull down “Actions” and select “Add”, you can set up the second account.
You can switch your account settings from the “Your email” pulldown.

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From version 3.0.0, supports IMAP.
If you want to use IMAP, check “IMAP” on the “Listen” tab on the “Settings” screen.

Set up your email client as follows.
Incoming Mail (IMAP) Server

localhostRequires SSL: No
Port: 8143
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