O2Popper

O2Popper is a mail proxy application that enables continuous use of mail software and systems that do not support Gmail's OAuth2. There are also erroneous transmission prevention functions.

Downloads

News

• 2022-12-263.0.1 release - Fixed SMTP bug (STARTTLS).
• 2022-12-223.0.0 release - Supports IMAP and allows registration of multiple accounts.
• 2021-12-242.0.0 release - Enabled to connect to a server other than Gmail.

Features

1. Supports both POP and SMTP
   • Two protocols, POP and SMTP, can be made compatible with OAuth2.
     (Supported also IMAP from version 3.0.0.)
2. Monitoring function
   • A GUI that can monitor the communication protocol is implemented.
3. SMTP block functions
   • You can block the mass mailing by mistaken Cc and Bcc.
   • You can cancel the transmission for up to 30 seconds.
   • You can remove the X-Mailer or User-Agent headers and send.
4. System tray menu
   • The operation menu is iconized in the system tray and does not interfere with other application operations.
5. Compatible with both Windows and macOS
   • Windows version and macOS version are available.
6. Open Source
   • The source code is on GitHub as an MIT license.
   • I do not collect personal information of users.

Confirmed operation email clients

• Outlook 2016
• Apple Mail
• Thunderbird (https://www.thunderbird.net/)
• Sylpheed (https://sylpheed.sraoss.jp/en/)
• EdMax (http://www.edcom.jp/edmaxtop.html)
• AL-Mail (https://www.almail.com/) ^*1 (2022-06-08 added)
• Shuriken (https://www.justsystems.com/jp/products/shuriken_pro/) ^*1 (2024-03-14 added)

Documentation

• O2Popper User’s Guide (Windows Version)
• O2Popper User’s Guide (macOS Version)
• How to get Client ID and Client Secret (2022-12-09 added)

Source Code

https://github.com/murataya/o2popper
(not include secret file for OAuth2)